Nexus® Software R5000.4.8 Basic Reservoir Simulation
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Nexus® Software R5000.4.8 Basic Reservoir Simulation
Introduction ...... i-1
Nexus® Software and Related Applications...... i-2 Nexus View® Software ...... i-3 PowerGrid™ Software ...... i-3 SurfNet™ Software ...... i-4 Nexus® Software and VIP® Programs ...... i-5
Nexus® Software and VIP® Programs ...... i-6
Nexus® Software Directory Structure ...... i-8
Nexus® Software Case File (.fcs File) ...... i-12
Nexus® Software Workflow Heat Map ...... i-14
File Naming Guidelines ...... i-15
Copying Keyword Files ...... i-16
Nexus® Software Documentation ...... i-17
Converting a VIP® Programs Model to a Nexus® Software Model ...... 1-1
Introduction ...... 1-1
Exercise: Convert a VIP® Programs Model to a Nexus® Software Model 1-5 Step 1: Create a Study and a Case ...... 1-5 Step 2: Use SimDataStudio™ Software to Select and Parse the VIP® Programs Files ...... 1-7 Step 3: Generate a Nexus® Software Simulation Data File...... 1-12
Nexus® Software R5000.4.8 Basic Reservoir Simulation i Contents
View the (Pre-simulation) Nexus® Software Model in Nexus View® Software ...... 1-17 Run the Simulation ...... 1-23 Analyze the Post-simulation Results ...... 1-27 Using Nexus View® Software ...... 1-27 Using SimResults™ Software ...... 1-29
Discussion Points ...... 1-34
Converting an ECLIPSE™ Model to a Nexus® Software Model...... 2-1
Overview ...... 2-1
Introduction ...... 2-2
Method 1: Use the E2V Converter Application ...... 2-3 Create a Study and a Case...... 2-3 Convert ECLIPSE™ Data to VIP® Programs ...... 2-4 Generate a Nexus® Software File in SDS™ Software and Submit the Job...... 2-7
Method 2: Invoke E2V Through SimDataStudio™ Software ...... 2-11
Discussion Points ...... 2-13
Total Model Workflow ...... 3-1
Introduction ...... 3-1
Create a Study and Case...... 3-2
Create Initialization Data with SimDataStudio™ (SDS) Software...... 3-3
Create Recurrent Data with SimDataStudio™ (SDS) Software ...... 3-17
ii Nexus® Software R5000.4.8 Basic Reservoir Simulation Contents
Generate a Nexus® Software Simulation Data File ...... 3-28
Run the Simulation ...... 3-33
View the Output File ...... 3-35
Discussion Points ...... 3-37
Run Multiple Cases ...... 4-1
Introduction ...... 4-1
Impact of Grid Size and Formulation ...... 4-2
Comparing Simulation Runs ...... 4-4 Nexus® Software, IMPES, 30x20 ...... 4-4 VIP® Programs, IMPES, 30x20...... 4-13 Nexus® Software, IMPLICIT, 30x20 ...... 4-15 Nexus® Software, IMPES, 60x40 ...... 4-18 Nexus® Software, IMPLICIT, 60x40 ...... 4-20
Discussion Points ...... 4-22
Visualization with SimResults+3D™ Software and Nexus View® Software...... 5-1
Introduction ...... 5-1
About SimResults+3D™ Software ...... 5-2
Exercise: Viewing Results in SimResults+3D™ Software ...... 5-3
Plotting Multiple Properties ...... 5-7
Nexus® Software R5000.4.8 Basic Reservoir Simulation iii Contents
Changing Display Attributes...... 5-8 Removing a Displayed Trace ...... 5-8 Editing the Plot Title and Legend ...... 5-9 Changing the Line Type ...... 5-10 Changing the y-axis ...... 5-11
Exercise: View Data in Spreadsheet ...... 5-14 View Current Data ...... 5-14 View Graph Data ...... 5-18
Exercise: Create Reports ...... 5-20
Saving Sessions in SimResults™ Software ...... 5-23
2D and 3D View in SimResults™ Software ...... 5-25
Introduction to Nexus View® Software...... 5-35
Exercise: View the Nexus® Software Model in Nexus View® Software ...... 5-37 Launch Nexus View® Software ...... 5-37 Data Selector...... 5-38 3D Viewer...... 5-45
Discussion Points ...... 5-59
Historical Production Data and History Matching...... 6-1
Introduction ...... 6-1
Introduction to the Perforation Wizard...... 6-2
Exercise: Create a Nexus® Software Model...... 6-3 Create a New Case ...... 6-3
Exercise: Load Well Trajectory and Perforation ...... 6-5
iv Nexus® Software R5000.4.8 Basic Reservoir Simulation Contents
Exercise: Reviewing and Importing the History Data ...... 6-17 Reviewing the Charts ...... 6-22 Averaging the Data (Required)...... 6-22 Setting Up and Performing the Averaging ...... 6-23 Interactively Adjusting Averaged Data ...... 6-24 Generating Date Records Automatically ...... 6-25 Generating Well Constraints...... 6-28 Generating the Nexus® Software File ...... 6-30 Simulate the Model in Nexus® Software ...... 6-32
Using SimResults™ Software to Examine Results...... 6-33
History Matching ...... 6-38
Adjusting the Data ...... 6-39 Modifying Property Data ...... 6-39 Understanding Aquifers ...... 6-40 Carter-Tracy Method ...... 6-42 Fetkovich Method ...... 6-44
Preparing for History Matching ...... 6-47
Results of the Model Visualization ...... 6-48
Exercise: Modeling an Aquifer...... 6-49
Adjust Fault Multipliers ...... 6-52
Adjust Contacts...... 6-54
Adjust Permeability ...... 6-56
Discussion Points ...... 6-58
Nexus® Software R5000.4.8 Basic Reservoir Simulation v Contents
Predictive Studies...... 7-1
Introduction ...... 7-1
Surface Network...... 7-2 Node Definition Data (NODES)...... 7-4 Node Connection Data (NODECON)...... 7-5 Network Pressure Constraints (CONSTRAINTS) ...... 7-6
Define Hydraulics Method ...... 7-7
Restarting Runs...... 7-9
Exercise: Running in Predictive Mode...... 7-10
Discussion Points ...... 7-25
Introduction to SurfNet Software ...... 8-1
Viewing Results in SurfNet Software ...... 8-1
Viewing Results in SurfNet Software: Loading Data from a Case ...... 8-2
Connecting a Group of Reservoirs into a Single Network . . . . 9-1
Introduction ...... 9-1
Exercise: Create a Multi-Reservoir Study and Case ...... 9-2
Join Multiple Models to Create a Single Multireservoir Model ...... 9-8 Connect the Networks in Multireservoir Builder Wizard...... 9-10
View the Multireservoir Model Data in SimDataStudio™ Software . . . . . 9-19
vi Nexus® Software R5000.4.8 Basic Reservoir Simulation Contents
Exercise: View the Multireservoir Model in Nexus View® Software . . . . 9-21
Exercise: Submit the Job ...... 9-23
View the Post-simulation Results ...... 9-24
Discussion Points ...... 9-28
SimConvert™ Software ...... 10-1
Introduction ...... 10-1
Understanding SimConvert™ Software...... 10-2
Exercise: Open a Study/Case in SimConvert™ Software ...... 10-3
Exercise: Using the SimConvert™ Software Interface ...... 10-5
Understanding the Map Data Export Options...... 10-7
Exercise: Export Map Data to Spreadsheet Format ...... 10-8
Exercise: Viewing the Exported Data ...... 10-11
Understanding the Production Data Export Options...... 10-13
Exercise: Export to Generic Spreadsheet...... 10-14
Understanding the Import Options ...... 10-17
Exercise: Importing Map/Plot Data...... 10-18
Exercise: Importing Rescue File ...... 10-21
Discussion Points ...... 10-25
Nexus® Software R5000.4.8 Basic Reservoir Simulation vii Contents
PowerGrid™ Software ...... 11-1
Introduction ...... 11-1
Exercise: Launch PowerGrid™ Software ...... 11-2
Exercise: Upscaling Workflow ...... 11-4
Exercise: Creating a Local Grid Refinement ...... 11-13 Define a Region ...... 11-13 Define a Local Grid Refinement...... 11-25
Discussion Points ...... 11-29
viii Nexus® Software R5000.4.8 Basic Reservoir Simulation i Introduction
Computer simulation is one of the most powerful methods available to optimize production of oil and gas from underground reservoirs. Using tools like Nexus Desktop® software, you can quickly model the flow of hydrocarbons and other fluids through formation layers, producing wells, and surface pipeline networks.
The Nexus® software is Landmark’s® next generation reservoir simulation product. It is the first reservoir simulation environment with a fully coupled, fully implicit surface/subsurface formulation. The Nexus software solves the problems of long turnaround times, painful information access, inaccurate/unstable models due to sole subsurface focus, and loose coupling.
The key benefits of the Nexus software are that it enables streamlined static to dynamic modeling, fully coupled/fully implicit solution for single or multiple reservoirs, and rapid, robust production and reserves forecasts.
The Nexus software provides the following functionality:
• Fully coupled network, facility, and subsurface modeling • Ability to model complex reservoirs supported with multiple fluid models • Datasets may be run individually and as a combination of individual reservoirs, coupled by a surface network. • Both serial and optimized parallel capability • Minimal tuning is required to achieve optimal performance. In many cases, no tuning is required. • Integration with other Landmark products such as DecisionSpace Earth Model, DecisionSpace Well Planning, and PowerGrid™ • Integration with existing VIP® programs such as SimDataStudio™ software • Ability to convert existing VIP projects to Nexus projects • Significant speed improvements over older commercial simulators
Nexus® Software R5000.4.8 Basic Reservoir Simulation i-1 Introduction
Nexus® Software and Related Applications
Landmark Graphics provides a complete suite of reservoir modeling applications that allow you to handle every part of the process, from data definition and import to gridding and simulation. The figure below gives an organization of the modules and its applications.
Listed below are some of the applications that constitute the respective modules in the DecisionSpace® software.
i-2 Nexus® Software R5000.4.8 Basic Reservoir Simulation Introduction
Nexus View® Software
The Nexus View® software is an integrated Nexus 3D view application that allows you to view simulation models (.vdb, RESCUE, and ECLIPSE™).
Application Description
Data Selector Load and display all the available data types.
3D Viewer Manage sessions, manipulate the view, launch other applications, access tools, and access the online Help system.
PowerGrid™ Software
The PowerGrid software is a reservoir modeling product that allows users to do advanced gridding and upscale geological models into simulation scale models.
Application Description
Advanced Manage properties, regions, and reservoir units, visualize Gridding property histograms, apply fault transmissibility multipliers, create local grid refinements, and extract/convert a portion of the grid.
Upscaler Upscale geological models into simulation scale models using a variety of static and fluid-based methods such as harmonic series, parallel tubes, and direct pressure solution. The PowerGrid software’s novel approach maintains the geological resolution near faults to prevent wells from switching from one side of a fault to another in areas where fault location is a key constraint. It also provides an automatic upscaling option which computes the optimum coarsening for a user-defined number of layers using any one of several property values.
Nexus® Software R5000.4.8 Basic Reservoir Simulation i-3 Introduction
SurfNet™ Software
SurfNet™ software allows the engineer to visualize and analyze the production and injection systems at whatever level of detail desired, including perforations, wellbore equipment, and the detailed surface facility model. Even for complex assets, the engineer can track flow paths and obtain an overall picture of the entire network at any point in time.
Application Description
Network Canvas The network canvas is the main display window for SurfNet software. The network schematic, along with requested properties for the network components, is displayed on the canvas. The user has access to all network data within the canvas, such as pressures and flow rates and their evolution in time, and can display the data either in numeric form or in charts. Critical sections of large networks can be selected and moved to a new canvas for detailed evaluation, and deactivated network sections can be eliminated from the canvas. The pictorial representation of the network allows the user to determine quickly and easily whether the network corresponds to its design.
Data Display Within the canvas, the user can display simulated network properties as a function of time. Different options for this display allow the user to highlight specific aspects of the data. Flow rates and pressures can be displayed directly on the network using a color map or in text adjacent to the network component. Data for an individual connection or node can be displayed as a function of time in charts that float above or can be docked to the canvas. Differing display modes provide a variety of approaches for studying the data, ensuring that unusual or unexpected behavior can be spotted and studied thoroughly.
Snapshot Tool After the data of interest is displayed on the canvas, the Snapshot Tool allows the user to capture the canvas or associated plots to include in reports or other documents. Multiple snapshots can be created and then saved in standard display formats for presentation.
i-4 Nexus® Software R5000.4.8 Basic Reservoir Simulation Introduction
Nexus® Software and VIP® Programs
Nexus and VIP simulators, along with the streamline simulator StreamCalc™ software, perform reservoir simulation as per user requirements.
Application Description
SimDataStudio Automates the creation of the initialization and recurrent data files that are submitted to the reservoir simulator.
Nexus Desktop Submit local or remote simulation runs on serial or parallel mode. Allows monitoring the simulation process while running.
SimResults™ Create line graphs, maps (2D and 3D), multi-graphs; search for and plot data; analyze loaded data; save datasets; and print graphs.
Utilities Other tools that help you convert and manipulate the data for your model. Landmark’s classic simulation applications updated for the DecisionSpace software: 3DView™, SimConvert™, GRIDGENR™, Array, Grid Calculator, Region Calculator, E2V, DESKTOP-PVT™, and PlotView™.
Nexus® Software R5000.4.8 Basic Reservoir Simulation i-5 Introduction
Nexus® Software Directory Structure
The Nexus directory structure is illustrated below:
Nexus software uses a data storage system called “VDB” database. This database is a folder structure that stores simulation grid and property input, observed data, and simulation results. The VDB folder is located directly under the project data folder, and since the entire simulation process is organized around the concept of a case study, the top-level directory name is the study name with a .vdb extension (that is, studyname.vdb).
For each VDB (i.e., study) there is a main control file (main.xml) within the top-level directory, which lists the simulation and observation case names that are included in subfolders below the VDB directory. Each simulation or observation case has a separate subdirectory, and each case can have several classes of data that reside in subdirectories under the case directory.
When you create a case, the case names default to the study name, followed by sequential numbers for multiple cases. However, these cases can be renamed during or after their creation.
In addition to output written to the VDB, multiple outputs are written to the scenario folder of the simulation case. The Nexus files, including the input and output files, are described in the following table.
i-6 Nexus® Software R5000.4.8 Basic Reservoir Simulation Introduction
File Description
.dbg Output file containing debug output, if debug output has been requested. See the DEBUG keyword in the “Run Control” section of the Nexus Keyword document.
.err ASCII output file produced when the keywords are parsed and the data is checked for consistency. In the event that the data is generating large numbers of warning messages, the first few warnings are output to the .rpt file, and the remainder to the .err file.
.fcs Nexus case file containing links to the Nexus input files (that is, the file submitted to the simulator for processing). This file can be manually written as a text file with valid Nexus keywords, or it can be automatically generated from within the SimDataStudio software.
.hyd Output file containing hydraulics output, if requested. See the OUTPUT HYDRAULICS keywords in the “Run Control” section of the Nexus Keyword document.
.log A log file created when you start a job in the Job Submittal window.
.map Output file containing map data, if the map format is specified as MAPFORM or MAPBINARY. The map data written is controlled by the MAPOUT keyword in the Run Control file.
.max Output file containing a summary of maximum changes and damping for each Newton iteration.
.maxijk Output file containing a summary of maximum changes and damping for each Newton iteration with i,j,k address of the cell.
.netsum Output file that reports the field production/injection summary (one line per timestep), obtained by summing the production/injection at the network sinks/source. This file is only present if NETSUM is specified in the Run Control file. The volumes reported in the .netsum file may be different from those reported in the .sum file for various reasons. These reasons include mixing of fluids in the network, separation or gas plant nodes in the network, and different PVT/separator methods used in different parts of the network.
.out Main ASCII output file from the simulator. It contains field summary data; region reports; recurrent data input reports; and well, perforation, network, and other reports (if requested by the OUTPUT keyword in the Run Control file). Note: the same field summary output is also written to the .sum file.
.plt Output file containing plot data if the plot format is specified as PLOTFORM or PLOTBINARY. The plot data written is controlled by the OUTPUT keyword in the Run Control file.
.rft Output file containing any RTF output that has been requested.
.rpt ASCII output file produced when the keywords are parsed and the data checked for consistency. It contains a report of the data read and any error and warning messages.
.runlog Output file containing a log of events that have occurred in the network, such as wells shutting or reopening, actions taken as a result of procedures, and so on.
Nexus® Software R5000.4.8 Basic Reservoir Simulation i-7 Introduction
File Description
.ss_field Output files containing spreadsheet output from the simulator. Spreadsheet output is requested using the SPREADSHEET keyword in the Run Control file. .ss_network .ss_regions .ss_targets .ss_wells
.sum Output file that reports the field production/injection summary (one line per timestep). The field production/injection is obtained by summing the production/injection from all the perforations in each well, and flashing them through the separator assigned to each well. The rates and cumulatives calculated in this manner should agree with the sum of the well rates and cumulatives, but may be different than what is ultimately produced/injected at the network sinks/sources.
.tssum Output file that reports information on how the timestep size was determined by the simulator.
.vdb Database structure for a study. Calculated simulation input and simulation results along with the observed data for each case are stored in output format readable by post-processing applications. Each case has its own folder in the .vdb with the data type classified and stored in the respective class folders. The plot data written is controlled by the OUTPUT keyword and the map data by the MAPOUT keyword. See the “Run Control, Output File Formats” section of the Nexus Keyword document for more keyword information.
.vds SimDataStudio case file containing all the data compiled during a particular work session within the SimDataStudio software. It stores the data and program options that you use when working on a case in the SimDataStudio software.
.wdb Well name cross-reference file.
.wrn Output file containing warning messages that may be generated by the simulator.
As illustrated above in the directory tree, all the output files are generated in the Scenario folder or the folder where the .fcs file resides.
The input files, including the pre-processor files such as the .gdb, .lgr, and .vds, generally reside in the same folder as the Scenario folder. Any location of these files other than the Scenario folder will require that they be mapped correctly in the .fcs file for them to be included in the simulator run. Normally, all included files used in Nexus input data files should reside in the nexus_data folder (default data folder) under the scenario folder.
i-8 Nexus® Software R5000.4.8 Basic Reservoir Simulation Introduction
Nexus simulation is a two-step process. The first step processes all input data through Standalone. Standalone will perform all of the error checking on the input data, and then write data summaries and error messages to the Standalone report (.rpt) file. Standalone also generates an .err file which will contain any warning messages about potential data inconsistencies. Note that this first step does not perform any simulator initialization calculations, and volumetric reports will not be output from this step. The second step is to run the Nexus simulator. This step performs all simulation calculations.
Nexus® Software R5000.4.8 Basic Reservoir Simulation i-9 Introduction
Nexus® Software Case File (.fcs File)
The Nexus case file (casename.fcs) is the file submitted to the simulator. It is like the VIP initialization (*i.dat) and recurrent (*r.dat) files, with two major differences:
• The Nexus software does not require a separate simulation file for initialization and recurrent run.
• The Nexus *.fcs file is a master file that provides the paths to separate data files.
The SimDataStudio software allows you to automatically create the simulation data file (*.fcs), and most of the data can be either imported from external text files or VIP format files, or entered manually. When the file is generated, the data files are placed in a subdirectory under the case directory named nexus_data.
If you view the *.fcs file from within the SimDataStudio software, then all of the links to the keyword files are click-able. If you view the *.fcs file in a text editor, they will not be click-able. Instead, you will have to open the data subdirectory, where all of the keyword files can be edited.
Note that the SimDataStudio Nexus file generation panel allows you to define a different directory path or filename for the data files before the *.fcs file is generated. However, if the path/filename are manually changed after the case file has been generated, the *.fcs file will not find the data.
Hence, if the Landmark software is not used to manage studies and cases, and the user instead works directly with the files and directory structures through the operating system, then care must be taken so the *.fcs file does not become separated from its dependent nexus_data subfolder. If this happens, then the run will not be able to find the proper keyword files with which to work.
i-10 Nexus® Software R5000.4.8 Basic Reservoir Simulation Introduction
The following figure shows the contents of a typical *.fcs file:
Nexus® Software R5000.4.8 Basic Reservoir Simulation i-11 Introduction
Nexus® Software Workflow Heat Map
Eclipse Grid, .INIT Datastore .UNRST
Rescue Generate and Re sc ue Volume of Region Histogram Extraction Da ta st ore 3D Model Interest Ma na ge r manipulate the geological scale model. Refinement Property Fault. VIP VDB Da ta st ore Manager LGR Manager Multiplier Output file is .vdb
SimConvert
Nexus View PowerGrid GridGenr/ Upscaling Array Eclipse Grid, .INIT Datastore .UNRST
VDB VDB (CLAC CLASS) (CLAC CLASS)
OpenWorks Well & Platform AssetPlanner Datastore information Define wells, w ell plans, perforation AssetPlanner Well & Platform Wells, Well Plans, zones and surface Datastore information Per fs network facilities.
Output file is .vdb
PetExperts GAP SimConvert VDB Datastore Network (SPN CLASS)
SimDataStudio PerfWizard Eclipse Eclipse E2V Datastore .dat/.data Define al l the remaining reservoir VIP VIP SimDataStudio attributes (fluids, Datastore i.dat & r.dat temperatures, pressures, .etc).
Nexus Nexus .fcs & VDB Output files are Reservoir Nexus .fcs & Datastore nexus_data (Pre-Existing Rock & Fluid nexus_data folder folder Model) Parameters
Submit the input Job Submittal data to the Nexus Simulator simulation engine and capture the results.
Nexus Output files are Nexus Results Output Files va rious AS CII f iles VDB & .vdb
Analyze & SurfNet SimResults Nexus View Visualize results.
i-12 Nexus® Software R5000.4.8 Basic Reservoir Simulation Introduction
File Naming Guidelines
Unless you are very familiar with the Nexus directory structures, the following guidelines are suggested:
• For Nexus datasets, maintain each individual reservoir in a separate Study and directory. Maintain a separate Study and directory for the Nexus multi-reservoir model.
• When using VIP files with the Nexus software, give corresponding VIP and Nexus models the same name, using an identifying suffix for the Nexus models (for example, cobalto_falc_nexus).
• Name the corresponding SimDataStudio (.vds) file using the same name as your Nexus case file (this is the default).
Also, do not use any of the following in your directory or filenames:
• Blank spaces • Special characters
Nexus® Software R5000.4.8 Basic Reservoir Simulation i-13 Introduction
Copying Keyword Files
Instead of using Landmark software to manage studies and cases, some advanced users prefer to work directly with the files and directory structures in Microsoft Windows, and create multiple copies of case data for use in iterative scenarios.
If you are working this way (through the operating system, rather than through Landmark’s interface) and you want to make a copy of the data files in one case for use with another case, you must copy both the .fcs file and the corresponding data subfolder (nexus_data) to the other case. If the .fcs file becomes separated from its dependent nexus_data subfolder, it will not be able to find the proper keyword files needed.
The nexus_data subfolder must be in the same location as the .fcs file, as shown in this illustration:
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Nexus® Software Documentation
Nexus Desktop software provides a wide variety of help documents. Application-specific help is also available in many application windows.
The following table shows documentation available in .pdf and .html format and how to access it.
Documentation Format Menu Selection(s)
Nexus Online Help HTML Help > Nexus User Guide
Input Utilities HTML or PDF Help > Input > [Utility Name]
Keyword and PDF Help > Simulators > [Manual Name] Technical Reference Manuals
Output Utilities HTML or PDF Help > Output > [Utility Name]
You also have easy access to Nexus or VIP example models through Help > Examples.... There are example datasets of black oil and compositional models for VIP and Nexus software.
Warning:
The exercises that follow have been tested with Nexus versions 5000.4.6, 5000.4.7, and 5000.4.8. Using versions older than 5000.4.6 may result in errors for some exercises.
Nexus® Software R5000.4.8 Basic Reservoir Simulation i-15 Introduction
i-16 Nexus® Software R5000.4.8 Basic Reservoir Simulation Chapter 1 Converting a VIP® Programs Model to a Nexus® Software Model
This chapter presents the first in a series of workflow exercises that will help you learn how to use the basic graphical user interface (GUI) Nexus Desktop®.
Introduction
In this chapter, you will learn how to convert a VIP® programs model to a Nexus® software model. The conversion process is performed rapidly with the SimDataStudio™ (SDS) software. Once created, the Nexus model is analyzed visually at both pre- and post-simulation conditions. To do this, you will: • Start the Nexus software.
• Create a study and a case.
• Use the SDS application to:
— Select and parse VIP files. — Analyze and/or modify the model parameters. — Generate Nexus files. • View the pre-simulation Nexus model in the Nexus View® software.
• Run the Nexus simulation model.
• Analyze the post-simulation results in both the Nexus View and SimResults™ software.
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Note
In this instance, the demo dataset (original VIP model) happens to describe a dipping and petrophysically heterogeneous black oil reservoir. This reservoir has 25 producing wells and is discretized into 9000 cells. The VIP to Nexus workflow, however, would be similar for all types and sizes of reservoir models. The original VIP model consists of two files. If you would like to view these files prior to the conversion process, use Windows Explorer to go to C:\Basic_Nexus\ws1 and open SPE916i.dat (the initialization file) or SPE916r.dat (the recurrent data file) using the Notepad application.
The menu options at the top of the window access drop-down menus that allow you to manipulate studies and cases, control toolbar and workspace views, launch other applications, and access the online Help system.
The following tables describe the Nexus standard tools icons:
Icon Description
Launches the SimDataStudio software. You can use the SimDataStudio software to view and edit existing Nexus models, convert ECLIPSE™ and VIP cases to Nexus cases, and build entirely new Nexus cases.
Launches the GRIDGENR™ software. You can use the GRIDGENR software to create grids and populate them with reservoir properties.
Launches the Array Calculator software. You can use the Array Calculator software to populate grids with arrays.
Launches the Grid Calculator software. You can use the Grid Calculator software to perform specialized calculations on the properties in a grid.
Launches the Region Calculator software. You can use the Region Calculator software to generate specialized reports on regions in the project that are not defined as IREGIONs.
Launches the E2V utility. You can use the E2V software to convert ECLIPSE data to VIP data.
1-2 Nexus® Software R5000.4.8 Basic Reservoir Simulation Chapter 1: Converting a VIP® Programs Model to a Nexus® Software Model
Icon Description
Launches the SimConvert™ software. You can use the SimConvert software to import/ export data to and from a VDB.
Launches the DESKTOP-PVT™ software. You can use the DESKTOP-PVT software to generate PVT properties or develop a mathematical model which can be used in compositional reservoir simulation models in Nexus or VIP to analyze oil and gas production characteristics.
Launches the SimResults+3D™ software. You can use the SimResults+3D software to view and analyze the results of a simulation job. The SimResults+3D software combines a 3D viewer with a variety of different types of plots.
Launches the PlotView™ software. You can use the PlotView software to view plots of simulation data.
Launches the 3DView™ software. You can use the 3DView software to view grid data in 3D and to run the PowerGrid application.
Launches the Nexus View software. You can use the Nexus View software to view grid data in 3D and to run the PowerGrid™ software.
Launches the User Editor tool. This editor is whatever editor application you have configured as the default editor for plain text files or files with specific name extensions (such as .fcs).
Launches the PowerGrid software. You can use the PowerGrid software to prepare your grid for the simulation process, calculate and create properties, make histograms and scaling grids
Launches the SurfNet software. You can use SurfNet to view the initial Surface Pipe Network and the variation with time using the output of the Nexus simulation. SurfNet can also be used to create surface network templates for use in building Nexus models with SimDataStudio.
The following tables describe the Nexus study and case management icons:
Icon Description
Launches the Network File Chooser dialog box, where you can select an existing study or create a new one.
Nexus® Software R5000.4.8 Basic Reservoir Simulation 1-3 Chapter 1: Converting a VIP® Programs Model to a Nexus® Software Model
Icon Description
Reloads the selected study. You can use this tool to refresh the study when you have generated new data that does not display in the main Study panel.
Closes the selected study. Closing the study will not delete it from the disk.
Creates a new simulation case in the currently selected study. Note: The case is not permanently written to disk until it is populated with data using a Nexus tool application or by running a simulation job.
Renames the selected case with a new name that you provide. This tool also allows editing of the comment for the selected case.
Removes the selected case. Note: This option will remove the case permanently from disk.
Creates a Nexus job for the selected case. Only one job per case is allowed.
Creates a VIP job for the selected case. Only one job per case is allowed.
Creates a StreamCalc™ software job for the selected case. Only one job per case is allowed. To run a StreamCalc job after a Nexus job, remove the Nexus job and create a StreamCalc job.
Removes the selected job. No job files are removed from disk.
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Exercise: Convert a VIP® Programs Model to a Nexus® Software Model
Step 1: Create a Study and a Case
1. Launch “Nexus Desktop 5000.4.8” by clicking the ( ) icon on your desktop or using the Start menu: Start >Programs>Landmark>Nexus Desktop 5000.4.8.
The Nexus Desktop window displays.
2. Click the “Open Existing or Create a New Simulation Study” icon ( ) on the Nexus Desktop toolbar to display the Network File Chooser window.
• Navigate to the “C:\Basic_Nexus\WS1” folder.
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• Type “vip_nexus" in the File name text field, then click Open. This will create a study with the name of vip_nexus.vdb in WS1 folder.
By default the application assigns the same case name as the study name. For this exercise, click OK to accept the default case name.
File Management Note
This process automatically saves a new folder called vip_nexus.vdb. This is the VDB folder that will serve as the repository for future case information. A file named main.xml is also created at this time and is placed within the VDB folder.
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• Highlight the "vip_nexus" case by clicking on it. Now, most of the icons in the tools menu are activated. Also, all possible information of this case is listed in the viewer panel.
Step 2: Use SimDataStudio™ Software to Select and Parse the VIP® Programs Files
1. Make sure the new case name (vip_nexus) in the tree is highlighted.
2. Click the SimDataStudio icon ( ) on the application toolbar.
The SimDataStudio software opens with the New SimDataStudio Case dialog box open.
The case name (name for the new .vds file), filenames, and their locations are filled in by default using the selected case. While the .vds filename is not required to be the same as the Nexus study or case names, it is strongly recommended for clarity that the .vds use the same name as the Nexus case.
3. Make sure Create a new Data Studio case is toggled on and that the Nexus case checkbox is checked on.
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4. Click OK to close the dialog box and create an empty case.
The New SimDataStudio Case dialog box closes and the SimDataStudio window opens.
File Management Note
This process saves a vip_nexus.vds file and a vip_nexus.wdb file at the same level as the VDB folder.
Next, you need to parse the VIP model.
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5. Select Simulation Data > Parse VIP Data File > CORE+EXEC files on the SimDataStudio menu bar or click the Parse icon ( ).
Note
Make sure the tool tip says “Parse VIP-EXEC and VIP-CORE data files” because there are several icons that are very similar.
The Select VIP-CORE Data File dialog box opens automatically first to Files of type i.dat.
6. Navigate to the C:\Nexus_basic_data\WS1 folder, select spe916i.dat, and click Open.
The File Selection dialog box changes to display files of type r.dat.
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7. Select spe916r.dat. Click Open.
A message box displays showing the files that have been selected to be parsed and advising that this operation will overwrite all current data.
8. Click OK to proceed.
The SimDataStudio software parses the VIP files and stores the data as a binary SimDataStudio case file (.vds).
As the files load, you see the filenames along with a progress indicator at the bottom of the window.
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When completed, you will see the data listed in the window at the bottom of the SimDataStudio software. You can click between the i.dat tab and the r.dat tab to review all of the data.
9. Select File > Save Case to save your work so far.
At this point, the SimDataStudio software has only been used to parse the original VIP files.
Within the SimDataStudio software, however, you can analyze and edit the model parameters before re-saving the files in either VIP- or Nexus- compatible format. For this exercise, you do not need to modify the data.
Step 3: Generate a Nexus® Software Simulation Data File
You can now use the parsed data to generate Nexus-compatible data files. There are two options:
• Generate initialization files only.
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• Generate initialization and recurrent files (full model). The initialization file contains limited information, a time-zero snapshot with no references to time-dependent data. This file is useful for error-checking and validating the quality of a model prior to simulation.
The recurrent data file includes information concerning run control parameters, well files, and other time-sensitive instructions for the simulator.
For this exercise, you want to generate the full model using both types of files.
To generate the simulation data file:
1. Select Simulation Data > Generate Simulator Data File > Nexus files, or click the Generate Nexus Data files icon ( ) on the SimDataStudio toolbar.
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The Nexus Data Set Generation… dialog box displays.
The Nexus case data file (.fcs), which is the simulation input file, is entered by default.
While changing the path or filename for the .fcs or .vdb files is not recommended, if you need to do so, you can click the Browse icon to the right of the text field and use the file selection dialog box that appears to select an alternate location and/or filename for the .fcs or .vdb file.
At this point, you can click in the Data Section tree to select or deselect specific data. However, for this exercise, accept the defaults.
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2. Make sure the Structured grid input format box is checked.
3. Click Generate to generate the Nexus case file.
A progress monitor displays while the conversion is in progress. The conversion should take a few seconds.
File management note
This process creates a number of new files, including the .fcs file, and a new folder. You can view this in Windows Explorer to verify.
When completed, the following message box should appear indicating that the Nexus dataset has been generated successfully.
4. Click OK to close the message box.
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The generation.log file is now open at the bottom of the SimDataStudio window (the vip_nexus_nexus_generation.log tab is selected).
5. Scroll through the file to review the generated data.
Any errors or warnings will appear in red text. Messages in blue text provide helpful information about the conversion.
Standard editing controls are provided so you can edit the data if needed.
6. Click the vip_nexus.fcs tab to review the .fcs file that was generated.
This .fcs file is a master file that points to all properties in the Nexus model. Scroll through the file to see the list of all property files (.dat).
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If you click one of the .dat files (for example, vip_nexus_init equil.dat under Initialization Files), the vip_nexus-init_equil.dat tab opens.
The initialization data displays as follows:
7. Click the Save icon( ) on the SimDataStudio toolbar to save the model.
8. Select File > Exit to close the SimDataStudio software.
Run the Simulation
Once you have created the simulation data file (.fcs), you can submit the job for simulation. Follow the steps below.
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1. Select "vip_nexus" case on the "Nexus desktop" window and from the menubar, select File > Nexus Job, or click on "Create New Nexus Simulation Job" icon ( ) .from the application toolbar. The Nexus Desktop window will change to a view similar to that shown below.
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In the Session tree (left window), the Nexus case files are listed. If you click any of those files, the detail will be displayed in the Viewer panel (right window).
Note that the User Editor icon ( ) and the Reset icon ( ) are now activated. The User Editor icon ( ) lets you open and edit the Nexus case file; and the Reset icon ( ) lets you reload the new edited file.
2. Click vip_nexus Nexus Simulation in the Session tree to bring back the Job Submittal view.
The Nexus software will attempt to complete the fields automatically, with all available information for you.
If you want to change a path or select different file, click the ( ) icon after the option you want to change. If the ( ) icon is not activated, make sure the option is on by checking its checkbox.
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3. Accept the default setting and click Start.
The Job Progress is highlighted in the Session tree and the progress file is shown in the right panel.
While the simulation is running, the Timestep Table in the Session area is available to view.
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4. Click the Timestep Table. A result table and plot are displayed in the Viewer panel. The status information will be displayed and updated in real time.
You can change the background color by right clicking on the monitoring graph window. To display a different variable vs. time, click on the variable heading column header. Click again on the variable column header to remove it from the plot window.
Note: The simulation monitoring plot window is intended only for simple plotting and job progress monitoring, for advance plotting the user can use SimResults which will be discussed shortly.
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You can select a line color, scale, type, and so on by right-clicking on a line.
5. When the simulation is completed, Standalone Report and Nexus Report in the Session area are available to view. Click the file in which you are interested to view it.
View the (Pre-simulation) Nexus® Software Model in Nexus View® Software
The Nexus View software was designed to enable collaboration among reservoir engineers and geoscientists. It provides an integrated workspace where members of the team can visualize their collective analysis in a single 3D workspace. The ability to share a single dynamic 3D viewer significantly improves productivity, shortens cycle times, and improves the quality of the team’s interpretation and the final outcome.
The two main components of the Nexus View software are the 3D Viewer and the Data Selector. The 3D Viewer allows you to manage sessions, manipulate the view, launch other applications, access tools, and access the online Help system. The Data Selector allows you to load and set the rendering options for all available data types.
Nexus® Software R5000.4.8 Basic Reservoir Simulation 1-21 Chapter 1: Converting a VIP® Programs Model to a Nexus® Software Model
In order to view a Nexus reservoir model in Nexus View, your Nexus model should have the map information stored under the case folder of your study (vdb). Generating unstructured Nexus files from SimDataStudio, will automatically create an initialization map under the case folder in the vdb. However, for a structure models, the user must run the model before being able to visualize the initialization data.
To view the Nexus model in the Nexus View software:
1. Click the Nexus View icon ( ) on the application toolbar. The 3D Viewer window appears with the 3D gird loaded. There are two tabs on the upper left border, “Data Selector” and “Display Settings”.
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Click on the Data Selector tab, the vip_nexus.vdb file and its path should be displayed in the Project panel. Switch the data class from RECUR to INIT. A warning message will ge generated, indicating the RECUR grid data will no longer be in the view. Click Close to dismiss the message.
2. If multiple cases are loaded in Data Selector, click the drop-down arrow and select vip_nexus.vdb.
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In the Data Selection area, select POR, the simulation model displays POR in the 3D Viewer window. Note that the PROPERTY list can be sorted alphanumerically by clicking the Property heading.
3. Hold and drag your left mouse button to rotate the display on an axis.
4. Hold and drag both your left and right mouse buttons (or use the scroll wheel) to zoom in or out.
5. Hold and drag your middle mouse button to translate the grid within the view.
6. Click the Reservoir Model Inquiry icon ( ) on the 3D Viewer toolbar and then click a cell in the 3D grid.
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A box opens with cell information.
You can select any property to display from the Values selection list and then click a grid cell.
The selected cell highlights within the display and the corresponding property values are shown.
7. Click the Reservoir Model Inquiry icon ( ) again to close the grid inquiry.
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8. Select View >Workspace from the 3D Viewer drop-down menubar to display the Workspace area in the left side of the 3D Viewer window.
Analyze the Post-simulation Results
You can analyze the simulation results in the Nexus View software or within the SimResults application.
Using Nexus View® Software To view the final model in the Nexus View software, use the following steps:
1. If Nexus View is not already open, select "vip_nexus" case and open "Nexus View" by clicking the ( ).
2. In the Data Selector, make sure vip_nexus.vdb is in the Project list.
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The RECUR option should be in the Data Selection pane in the vip_nexus drop-down list. Switch to RECUR data class if necessary. The Oil Saturation map should be shown by default.
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3. Move the timestep icon on the 3D View panel and observe the saturation change.
Using SimResults™ Software You can also view the model in the SimResults software. The SimResults software has many simulation-specific features, including the ability to:
• Create line graphs. • Plot solution data. • Plot RFT data. • Create multi-graphs. • Search datasets and create plots of the required data. • Create derived quantities. • Analyze loaded data. • Iinterpret and execute graphics run files (.grf). • Create a .grf file from a working session. • Save datasets. • Print graphs.
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1. Select "vip_nexus" case and click on Simresults icon ( ). Plot and analyze. In the coming chapters there will be more examples on using SimResults.
The 3D module allows you to display solution grids in 3D. A separate license is required for the SimResults+3D software.
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1. To view the 3D grid, click on File>Open and select the study (.vdb), in this example "vip_nexus.vdb"
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2. Select "Grid data" from "VIP vdb case selection" window:
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3. Drag the ROOT grid into an empty drawing space. Then visualize the desired property by dragging it onto the "Grid".
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Discussion Points
You should now be able to answer these questions about converting a VIP model to a Nexus model:
• What purpose does the SimDataStudio (SDS) software serve when converting a VIP model to a Nexus model?
• What are some differences between the pre- and post-simulation conditions?
• What must be done to VIP files before they can be used to generate a Nexus simulation?
• What is the purpose of the Data Selector?
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1-34 Nexus® Software R5000.4.8 Basic Reservoir Simulation Chapter 2 Converting an ECLIPSE™ Model to a Nexus® Software Model
This chapter describes two ways to convert an ECLIPSE™ model to a Nexus® software model.
Overview
In this chapter, you will:
• Use the E2V Converter application to:
— Create a study and case. — Convert ECLIPSE data to VIP® program data. — Generate a Nexus file in the SimDataStudio™ software and submit the job. • Invoke E2V through the SimDataStudio software.
Note
There is also a third method of converting model types. Click the SimConvert icon ( ) on the Nexus toolbar to use the SimConvert™ software to convert ECLIPSE array data to a VDB. This method is not covered in this chapter. For detailed information, click the SimConvert icon and select Help > Help Topics.
Nexus® Software R5000.4.8 Basic Reservoir Simulation 2-1 Chapter 2: Converting an ECLIPSE™ Model to a Nexus® Software Model
Introduction
The first workflow utilizes E2V, an application that recognizes the files and keywords comprising an ECLIPSE model, and converts them to an equivalent model in VIP format. The second method is performed entirely within the SimDataStudio (SDS) software and circumvents the intermediate step of creating initialization and recurrent files in the VIP format.
The first method (using E2V):
• Activates E2V directly from the Nexus and VIP Simulation window.
• Selects an ECLIPSE data file and converts it to VIP files.
• Uses the SimDataStudio software to select and parse the VIP files.
• Generates a Nexus file.
The latter two steps are very similar to the workflow conducted in the previous chapter.
The second method (using SDS):
• Uses the Load ECLIPSE Data option directly from the SimDataStudio window.
• Selects and parses an ECLIPSE file.
• Generates a Nexus file.
Before beginning, you may wish to view the ECLIPSE data files outside of the Nexus software. This workshop’s data is from the SPE Comparative Solution #9, a model used for simulator benchmarking.
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Method 1: Use the E2V Converter Application
Create a Study and a Case
1. Click the Create New Study icon ( ) on the Nexus Desktop® application toolbar and create a new study under WS2\Output folder.
2. Name this new study eclipse_nexus. Change the case name to eclipse_nexus1 when prompted.
The new study and case are added to the Session tree in the Nexus Desktop window.
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Convert ECLIPSE™ Data to VIP® Programs
1. In the Nexus Desktop window, click the eclipse_nexus1 case in the Session tree to highlight it.
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2. Click the E2V Converter icon ( ).
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3. Select the ECLIPSE file (.DATA) to be converted by clicking Browse... and navigating to WS2 folder.
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4. Select the SPE9.DATA file and click Open.
5. Specify the VIP file to be created by clicking on Browse... and navigating to WS2\Output folder.
6. In the “File name” text box, type “eclipse_nexus1” and click Save.
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Your E2V Converter window should now appear as follows.
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7. Click Convert to VIP. A message box saying that the tuning was skipped appears, click OK to proceed.
The progress bar indicates the progress of the conversion. The data files are listed in the bottom panel of the E2V Converter as the data is converted. When the conversion is complete, the following message appears:
8. Click OK.
9. Click Exit to close the E2V Converter.
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Generate a Nexus® Software File in SDS™ Software and Submit the Job
Now that you have a VIP model, you are at a point similar to where you were in Chapter 1.
1. Start by highlighting the eclipse_nexus1 case in the Nexus Desktop window.
2. Click the SimDataStudio icon ( ).
3. When the New SimDataStudio Case dialog box appears, check Create a new case by parsing an existing VIP data set.
4. Click the Folder icon ( ) to the right of the VIP-CORE data file text field.
The Select VIP-CORE Data File dialog box appears.
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5. Choose eclipse_nexus1i.dat from WS2\Output folder and click Open..
6. Click the Folder icon ( ) to the right of the VIP-EXEC data file text field.
The Select VIP-EXEC Data File dialog box appears.
7. Choose eclipse_nexus1r.dat from WS2\Output folder and click Open.
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The New SimDataStudio Case window should appear as follows:
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8. Click OK.
9. Follow the steps under the "VIP to Nexus Workflow" section in Chapter 1 to generate a simulation data file (eclipse_nexus1.fcs).
You can then view the model in the Nexus View software, and submit the job as in Chapter 1.
10. Before proceeding to Method 2, be sure to save the case by selecting File > Save Case in the SimDataStudio software, then close the SimDataStudio software.
To learn more about the functionality of the E2V Converter, select Help > Input > E2V User’s Guide.
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Method 2: Invoke E2V Through SimDataStudio™ Software
This second method converts an ECLIPSE model to a Nexus model by using a feature in the SimDataStudio software that skips the intermediate creation of a VIP dataset. The SimDataStudio software directly stores the applicable ECLIPSE data in the SimDataStudio case file.
1. Click the eclipse_nexus study in the Nexus and VIP Simulation window to highlight it.
2. With the “eclipse_nexus” study highlighted, the Create New Simulation Case icon ( ) on the toolbar and create a new case called eclipse_nexus2.
The new case is added to the study/case tree in the Nexus Desktop window.
3. Click the eclipse_nexus2 case in the study/case tree to highlight it, then click the SimDataStudio icon ( ).
The SimDataStudio software opens with the New SimDataStudio Case dialog box open.
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4. Make sure Create an empty Data Studio case is toggled on and that the Nexus case checkbox is checked.
5. Click OK to close the dialog box and create an empty case.
6. Click the Load Eclipse data icon ( ) on the SimDataStudio toolbar.
7. Navigate to WS2 folder and select the SPE9.DATA ECLIPSE data file.
8. Click Open.
A SimDataStudio message appears advising that you are about to parse SPE9.DATA into the active case and that this will overwrite the initialization and recurrent data.
9. Click OK to proceed.
The ECLIPSE file is converted to a .vds file, and the SimDataStudio window is populated with the ECLIPSE data.
At this point, you are ready to generate a simulation data file, view the model in the Nexus View software, and submit the job as previously described.
Optional
Note that you can review the data in the individual panels in the SimDataStudio software and edit as needed. When you generate the simulation data file, you will get an error message if necessary information is missing. For example, try opening the Initialization Data panel and deleting the entry in the Reservoir Pressure field. Now, click the Generate Nexus Files icon ( ) to generate a Nexus model. As you see, you will get an error message.
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Discussion Points
You should now be able to answer the following questions:
• What are two ways to convert an ECLIPSE model to a Nexus model?
• Is there any other way to convert an ECLIPSE model to a Nexus model?
• Which method do you (or will you) use? Why?
• Which file format does the ECLIPSE data change to in the SimDataStudio software?
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In this chapter, you will compile data for a simple reservoir model with two components (black oil model). You will be provided with enough petrophysical and structural data to determine the optimum position and perforation locations for a single well in this undeveloped field. Current facilities can only handle a maximum water rate of 500 STB per day and 50,000 MSCF per day. The duration of the simulation is four years.
You will develop a flank portion of an undeveloped reservoir fault block. A structural interpretation based on seismic data and ties to other areas of the field indicates that this portion of the reservoir is a dipping structure with a fairly constant thickness. Geologically, the reservoir is interpreted to have much areal continuity, with stratification in the vertical direction. Other areas of the field have been successfully simulated using a layer-cake model. A similar eight-layer cake model has been developed based on analogs from other areas of the field. Based on these analogs, the area is thought to have a gas-cap and an oil- water contact within the zone, which is thought to be productive.
Introduction
In this chapter, you will:
• Create a study and case. • Create initialization data with the SimDataStudio™ (SDS) software. • Create recurrent data with the SimDataStudio software. • Generate a Nexus® software simulation data file. • run the simulation. • View the output.
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Create a Study and Case
The first procedure is to create a new study and case for the strip model and open it as the active case within the SimDataStudio application.
1. In the Nexus Desktop® software window, click the Open Existing or Create New Simulation Study icon ( ).
2. Browse to the WS3 directory and type strip as the study name, then click Open.
3. When the Create Case window appears, change the case name to run1.
4. In the Session tree, select the run1 case you just created.
The run1 case is highlighted, and the toolbar icons become active.
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Create Initialization Data with SimDataStudio™ (SDS) Software
Next, you will use the SimDataStudio assistant to create your initialization dataset.
1. Click the SimDataStudio icon ( ).
The SimDataStudio application opens to the New SimDataStudio Case dialog box.
2. Accept the default path and filenames.
3. Set the Case creation mode to Use assistant to create a simple initialization data set.
4. Click OK.
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The first assistant panel prompts you for a start date, unit, title, and grid system.
5. Use the Start Date drop-down menu to graphically set the date to January 1, 1995.
6. Set the three Title lines to:
WS3: Strip Problem
7. Select Cartesian as the Main Grid coordinates.
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8. Define a grid that has:
• 15 gridblocks in the X direction (NX)
• 5 gridblocks in the Y direction (NY)
• 8 gridblocks in the Z direction (NZ)
Once the required parameters are entered, the Next button becomes active.
9. Click Next.
The second assistant panel prompts you to input grid geometry information. The grid was devised to provide greater resolution in the areas of the oil column, with less resolution in the gas cap and aquifer.
10. Make sure that the Property drop-down menu has DX - Length of gridblock in the X direction measured along horizontal selected.
11. Select the Variable radio button, and select the corresponding parameter to be in the X direction.
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12. Define the lengths of the 15 gridblocks by typing the values shown in the following:
13. Select DY - Length of gridblock in the Y direction measured along horizontal from the Property drop-down menu.
14. Select the Variable radio button and select the corresponding parameter to be in the Y direction.
15. Define the lengths of the 5 gridblocks by typing the values shown in the following:
16. Select DZ - Gross vertical thickness of gridblock from the Property drop-down menu.
17. Select the Variable radio button and select the corresponding parameter to be in the Z direction.
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18. Define the thickness of the 8 gridblocks by typing the values shown in the following:
19. Select DEPTH - Depth to top of gridblock from the Property drop-down menu.
20. Select the Dip Angle radio button (just below the Variable button).
21. Assign the depth of the first gridblock (top of reservoir) to be 9000 feet, and give the reservoir a constant dip angle of 12 degrees in the X direction, and 0 degrees in the Y direction.
Now that arrays for DX, DY, DZ, and DEPTH are defined, the Next button becomes active.
22. Click Next.
The third panel prompts you to enter grid physical properties.
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Porosity is only specified in one direction (Z). It is assumed to be uniform horizontally within each layer (zone), but to vary between layers.
23. Select POR - Gridblock porosity from the Property drop-down menu.
24. Select the Variable radio button and set its corresponding parameter to in the Z direction.
25. Enter the values shown in the following:
26. Select KX - Gridblock center permeability in X direction from the Property drop-down menu.
27. Select the Variable radio button, and set its corresponding parameter to in the Z direction.
28. Enter the values as shown in the following:
29. Select KY - Gridblock center permeability in the Y direction from the Property drop-down menu.
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30. Select the Multiple of radio button and set its corresponding parameters to KX and 1.0, as shown in the following.
31. Select KZ - Gridblock center permeability in the Z direction from the Property drop-down menu.
32. Select the Multiple of radio button and set its corresponding parameters to KX and 0.1, as shown in the following.
This sets vertical perm equal to one-tenth of areal perm.
33. Click Next.
The next panel prompts you for water properties, reservoir constants, and standard conditions.
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34. Enter the data shown in the following:
35. Click Next.
The next panel for entering phases and regions should require no changes. By default, the fluid model is correctly set to Black-Oil, and all region-definition options are set to 1.
36. Click Next.
The next panel prompts you for water-oil table data. This panel and the next one (gas-oil table data) let you specify saturation-dependent rock properties, including water-oil (gas-oil) relative permeabilities, and capillary pressures.
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The assistant gives you the option of either building your rock property curves by defining the endpoints and exponents for a Corey Model Correlation, or by importing your saturation table data from an external file.
For this exercise, you will import the data.
37. Select the Import Table option.
38. Click Import.
The Select ASCII file with Saturation Table dialog box opens.
39. Navigate to WS3 folder , and select the stripkrw.inc file..
40. Click Open.
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A preview window shows you cross plots of relative perm vs. water saturation. You can use the Display selection drop-down menu to add capillary pressure to the display.
41. Click OK, then click Next.
42. Using the same procedure, import the gas-oil table data from the stripkrg.inc ASCII file.
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After importing the gas-oil table data, an automatic preview appears.
Note
Data from these two-phase systems are used to interpolate properties for situations where three phases are simultaneously present. The interpolation is computed using either Stone’s I permeability model, Stone’s II permeability model (default), or a Saturation Weighted interpolation.
43. Click OK to close the preview window.
44. Click Next.
The next panel prompts you for the black-oil PVT data. The properties entered here are derived from standard differential liberation and constant compositional expansion tests on reservoir fluids.
45. Using the same procedure for importing tables, import the black-oil PVT data from the ASCII file named strippvt.inc.
46. Click OK to close the preview, then click Next.
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47. The next panel prompts you for the last tabular data. The equilibrium table data is used to create an initial reservoir model that is in a steady state of equilibrium.
48. Enter the data as follows:
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49. Click Next.
50. When the Summary screen appears, verify that there is no red remark for Status (as follows).
51. Make sure the box for Structured grid input format is checked. Click Finish to populate the SimDataStudio interface with your inputs.
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Notice that, in the SimDataStudio software, none of the data status indicators are red. This confirms that all required data is present.
52. Click the Save icon ( ) on the SimDataStudio toolbar.
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Create Recurrent Data with SimDataStudio™ (SDS) Software
In this exercise, you will continue using the SimDataStudio software to create the recurrent data for the simulation. You will create data to simulate the reservoir from 1/1/1995 to 1/1/1999, producing from a single vertical well (W1) perforated in all the layers, and producing under set constraints.
1. In the SimDataStudio software, click the EXEC tab to bring it forward.
2. On the EXEC tab, double-click Utility Data.
3. Set the Start Date to 1 January 1995.
4. Set the End Date to 1 January 1999.
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5. Double-click Output Options in the EXEC data tree menu.
6. Right-click the spreadsheet and select Generate New Output Date List.
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7. Define Output Options in the Generate Simulation Date List window by clicking ( ).
8. Specify Print Options every 6 months for PERFS, WELLS, and FIELD. Note that FIELD is located in the Region Report section.
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.
9. Specify Plot Options every 6 months for WELL and FIELD.
10. Specify Map Options every 6 months for P, SO, SW, and SG.
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11. Specify the Restart Options every 2 years. Click OK.
Next, you will set the Well Names and Locations.
12. Double-click Well Names and Locations under Well Data in the EXEC data tree menu.
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13. Right-click the spreadsheet and choose Insert New Well.
• Define a well with the Well Name as W1 and an (I, J) Location of (5, 3).
14. Click OK.
Next, you will set Well Perforations.
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15. Double-click Well Perforations under Well Data in the EXEC data tree menu.
16. Right-click the spreadsheet and choose Add Wells Perforations.
The Add Perforations window appears.
17. Highlight W1 and set perforations from layer 1 to 8.
18. Click OK.
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19. Right-click the spread sheet and select Perforation Options from the menu to open the Perforation Options dialog box.
20. Deselect all options except the L-Layer Number and RADW-Wellbore Radius.
•Click OK to save the change and close the Perforation Options window.
• Manually set the RADW for W1 = 0.25.
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Next, you will set Well Constraints.
21. Double-click Well Constraints under Well Data in the EXEC data tree menu.
22. Select the By well radio button in the View Mode Selection panel in the bottom center.
23. Right-click the first cell under Well Type and choose Change Well Type for Cell to open the Select Well Type dialog box.
24. Set W1 to Producer, set fluid type to Oil, set units to Standard Conditions, and click OK.
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25. Right-click the first cell under Maximum Rate and select Change Maximum Rate for Cell to open the Select Well Rate Constraint dialog box.
26. Set the Maximum Oil Production Rate as 2000 STB/day and click OK.
27. Right-click the first cell under Bottomhole Pressure and select Change Bottomhole Pressure for Cell to open the Bottomhole Pressure Constraint Selection dialog box.
•Set Bottomhole Pressure as 1000 PSIA at a reference depth of 9000 feet and click OK.
Now, you will notice there are no red indicators either in the CORE data tab or in the EXEC data tab. Leave the SimDataStudio software open for the next exercise.
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Generate a Nexus® Software Simulation Data File
You can now use the entered data to generate Nexus data files.
1. Select Simulation Data > Generate Simulator Data File > Nexus files, or click the Generate Nexus files icon ( ).
Important
There are several similar icons. Please make sure you are clicking the correct icon (pause your cursor over the icon for a mouse-over description).
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The Nexus Data Set Generation... dialog box appears. Make sure the Structured grid import format box is checked.
The Nexus case data file (.fcs), which is the simulation input file, is entered by default.
While changing the path or filename for the .fcs or .vdb files is not recommended, if you need to do so, you can click the Browse icon ( ) to the right of the text field and use the file selection dialog box that appears to select an alternate location and/or filename for the .fcs or .vdb file.
At this point, you can click in the Data Section tree to select or deselect specific data.
For this exercise, accept the defaults.
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2. Click Generate to generate the Nexus case file. A warning box may appear, indicating the Nexus case file run1.fcs already exists. Click Yes to overwrite it.
File management note
This process creates a number of new files, including the .fcs file, and a new folder. You can view these in Windows Explorer to verify.
When the conversion is completed, the following message box should appear indicating that the Nexus dataset has been generated successfully.
3. Click OK to close the message box.
Note that the generation.log file is now open at the bottom of the SimDataStudio window.
4. Scroll through the file to review the data that has been generated.
Any errors will appear in red text. Messages in blue text provide helpful information about the conversion. Standard editing controls are provided so you can edit the data if needed.
5. Click the run1.fcs tab to review the .fcs file that was generated.
This .fcs file is a master file that points to all properties in the Nexus model.
6. Scroll through the file to see the list of all property files (.dat).
If you click one of the .dat files (for example, run1_init-equil.dat) under Initialization Files, the run1-init_equil.dat tab opens and displays the initialization data.
7. Click the Save icon ( ) on the SimDataStudio toolbar.
8. Select File > Exit to close the SimDataStudio software.
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Run the Simulation
Once you have created the simulation data file (.fcs), you can submit the job for simulation using the Nexus Job Submitter.
1. Make sure the run1 case is highlighted in the Session tree in the Nexus Desktop window.
2. Click the Create New Nexus Simulation Job icon ( ) on the application toolbar.
The name of the .fcs file is shown in the FCS File row.
3. Click Start.
The Job Progress file is displayed and updated automatically to follow the job progression.
The application checks the Nexus model for consistency. If there are no problems, it converts the file from ASCII to binary format and then passes control to the Nexus executable, which starts the calculation.
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The calculation may take a few minutes. If you need to stop the calculation at any time, click the Stop button and it will be stopped after the Standalone process is complete.
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View the Output File
The Nexus Job Submitter calls the standalone executables, which write a report containing error messages. This file is the .rpt. If something is wrong with your input data, then the .rpt file will point to a problem and describe it.
To view the contents of .rpt file from the "job submit" window, click "Standalone Report" under the Session tree of run1 case. The file can also be opened directly for searching keywords/values using a text editor (predefine) using the icon ( ).
Another output file is .out, which contains a wide variety of information, such as field summary data, region reports, recurrent data input reports, well, perforation, and so on.
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To view the contents of output report (run1.out), click the "Nexus Report" under the session tree of run1 case. The file can also be opened directly for searching keywords/values using a text editor (predefine) using the icon ( ).
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Discussion Points
You should now be able to answer the following questions:
• Why was the geometry grid created?
• How are the input values for the porosity and permeability data different?
• What are the two ways to build your rock property curves?
• What should you do before initializing the model?
• During the job processing, how can you see the details and status?
• If errors were found in the output log of a job, what do you need to do to correct them?
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This chapter will demonstrate the impact of model size and different computation options on job simulation run times. Starting with a 30x20 grid for the halcon model, you will run the same model using different grid configurations and different formulations (IMPES or IMPLICIT).
Introduction
This exercise will help you run multiple cases using variations on the same data in the base case, so you can:
• Compare the results of using the VIP® programs and Nexus® software simulators on the same model.
• Compare the results using different formulation methods in the Nexus software.
• Compare the results using different size grids in the Nexus software.
In this exercise, you will:
• Create the base study and Nexus case halcon.
• Generate the Nexus model in the SimDataStudio™ (SDS) software and submit the case using the Nexus Job Submitter.
• Create a VIP case with the same model, and run it using the VIP Job Submitter.
• Create three additional Nexus cases with different configurations, and run them using the Nexus Job Submitter.
• Record run information in the VIP and Nexus data tables for comparison.
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Impact of Grid Size and Formulation
The numerical simulation of a reservoir model requires extremely complex calculations involving many coupled, non-linear equations. The number of individual equations used can be loosely determined by multiplying the number of gridblocks times the number of components. The number of gridblocks usually increases as their size decreases; the latter being desired to adequately represent the physics of fluid flow within the reservoir.
The equations are slightly different depending on the formulation used: the Implicit Pressure, Explicit Saturation formulation (IMPES), or the fully Implicit formulation (IMPLICIT). The solution of these equations, at finite timesteps, provides a way to estimate specific time-dependent changes in pressure, saturation, composition, and other key parameters for each gridblock and each well over the production period desired.
IMPES is much faster per timestep. However, because of the explicit treatment of mobility terms and capillary pressure (evaluation at N instead of N+1 timestep), it is much less stable and requires more and smaller timesteps compare to the IMPLICIT method. The classic situations that are problematic for IMPES are small gridblocks near wells, vertical gas percolation, and pinchouts. Each of these involve large gridblock throughput relative to its size over a timestep. In contrast, IMPLICIT will always require more RAM than IMPES, since more equations are being solved. However, since it is more stable than IMPES, the simulator is able to take larger timesteps.
The optimal choice between IMPES and IMPLICIT is then highly case-dependent. Usually, the deciding factors are:
• CPU time required to finish the simulation
• RAM required and available
• IMPES stability issues
• Special circumstances that require an IMPLICIT formulation (that is, radial refinements and grids, as well as dual porosity/permeability models)
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Parameter IMPLES IMPLICIT
MEMORY Less More
CPU TIME / STEP Less More
TIME STEPS More Less
TOTAL CPU TIME Care dependent
STABILITY Less More
DISPERSION Less More
A number of files are provided to you for use in this exercise. They are shown in the image below. Make sure your WS4 folder contains each of these files. If any are missing contact your instructor immediately.
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Comparing Simulation Runs
You are now ready to begin running multiple simulations to test the results of the two simulators, two formulations, and two grid sizes.
Nexus® Software, IMPES, 30x20
The first thing to do is set up the study and the base case, so that you can use the case management features to keep track of all your cases.
1. Create a new study named halcon within the WS4 folder. Accept the default case name of halcon.
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2. Open the SimDataStudio software, make sure Create an empty Data Studio case is selected, and click OK.
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3. Based on the following table, input the initialization data, and include all the appropriate parameters for this workshop.
Workshop #4 Initialization Data
Basic Options: Unit/Grid System Start Date 01 April 2001 (These are the files produced as export data from Array. They Use GRIDGENR Grid Files toggle on contain gridblock corner points and array data for the current model.) Grid Definition File halcon30x20.lgr Physical Properties File halcon30x20.cor Fault Definition File halcon30x20.fml
Basic Options: Output Data MAP Arrays POR PVR TX TY TZ Control PRINT Options Print None
Fluid Reservoir Constants Stock Tank Water Density 1.01 gm/cc
Water Formation Volume Factor 1.003 rb/STB
Water Viscosity 0.39 cp
Water Compressibility 3E-6 1/PSIA
Rock Compressibility / Temperature 4.E-6 / 180 F
Standard Pressure / Temperature 14.65 / 60 F
Initialization Data Reservoir Pressure / Depth 3900 psia at 9300 feet
Water-Oil Contact / Capillary 9385.0 / 0.0 Pressure
Gas-Oil Contact / Capillary Pressure 0.0 / 0.0
Saturation Pressure 2100.0
Rock Property Tables Water-Oil Table Import: halconkrw.inc
Gas-Oil Table Import: halconkrg.inc
Fluid Property Tables Black Oil PVT Table Import: halconpvt.inc
Hints:
• For inputting grid data, under Grid System, select option Use GridGenr grid files.
• Use IMPORT option for KRW, KRG, and PVT data.
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Now, you will be introduced to the Function application. The Function option can be used to calculate dependencies for arrays, either in tabulated or analytical form. You can:
• Represent some correlations between reservoir rock properties (analytical function).
• Calculate average values of a rock property array using information about its values in another reservoir location (interpolation function).
• Calculate volume-averaged values of a rock property array using known gridblock center values (volume-averaged function).
In this exercise, Function is used to eliminate certain regions from the model that do not materially contribute to the simulation.
4. From the SimDataStudio CORE tab, select Functions for Array Definition, and click the New (Insert) icon ( ).
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5. Set the function definition type to Interpolation.
6. Set the Input array to MDEPTH, and the Output array to POR..
Hint
Click ( ).
7. Set the Input-Output values for selected function as shown in the following:
8. Set the Input range for the Value range selection where to apply selected function as shown in the following:
Hint
Click ( ).
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9. From the EXEC tab, open the Utility Data option to verify that the Start Date is 01 April 2001, and to set the End Date to 01 April 2010.
10. Open Output Options. You should see two Run Date entries in the table corresponding to the previously entered Start/End dates.
11. Right-click within the table and select Generate New Output Data List from the popup menu that appears.
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12. Set the Plot and Map options as follows:
13. Use the well definition data generated to populate the Well Names and Locations table.
14. Open the Well Names and Locations table, right-click in it, and select Import wij File. Select halcon.wij from your WS4 directory.
The 10 wells (W1 - W8, D1, and D2), and their gridblock I, J locations for the current model are now in SDS.
15. Use the well definition data generated again to populate the Well Perforations table. Open the Well Perforations table and right- click it to select “Import Perforations from ASCII File”. Select halcon30x20.fpf from your WS4 directory.
83 perforations are spread out through your 10 wells. Well D2 contains the most perforations for the current model with 12.
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16. Open the Well Constraints table and set the View Mode Selection to By Constraint.
17. Set the first constraint as Well Type.
18. Right-click in the first cell in each column, and select the Change Well for cell option in the popup menu that appears.
19. When the Select Well Type window appears, set all 10 wells to Oil.
Once a constraint is defined for the first well, it can be cut and pasted into other wells.
20. For constraint Maximum Rate, set all 10 wells to 1000 STB/D.
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21. For constraint Bottomhole Pressure, define a limit of 1000 PSIA at depth of gridblock center with first perforation.
22. Select Simulation Data > Generate Simulator Data File > Nexus files, or click the Generate Nexus files icon ( ).
23. When the Nexus Data Set Generation... dialog box appears, click Generate to generate the Nexus case file.
24. Save the .vds file and exit the SimDataStudio software.
25. Submit this job by clicking Create New Nexus Simulation Job icon ( ).
26. Record these findings in the table found at the end of this chapter.
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VIP® Programs, IMPES, 30x20
1. Highlight the halcon study, and create a new case named halcon1. Make sure your new case resides directly under the halcon study instead of being a child of the previous case.
2. Click the Create New VIP Simulation Job icon ( ).
3. Notice that, in this case, both i.dat and r.dat files have been assigned automatically. Check both Core Data File and Exec Data File. You may reassign those two files by clicking ( ).
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4. Click Start to submit the job.
5. When the simulation completes, click Exec Output under the Session tree to open halcon1r.out and view the simulation output. Search the file and see what you can locate:
6. Record the findings in the table on page 5-19.
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Nexus® Software, IMPLICIT, 30x20
In this exercise, you will create a Nexus case with IMPLICIT formula and compare the result to the base Nexus case with IMPES formula.
1. In the Nexus Desktop® software window, create a new case named halcon2 under the halcon study.
To prepare for the new case, you need to modify two files from the basic Nexus case.
2. Copy the halcon_runcontrol.dat file, which is located at WS4\nexus_data folder, and paste it to the same location. Rename the new copied file to halcon2_runcontrol.dat.
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3. Open halcon2_runcontrol.dat using Notepad (or text editor of your choice), and add METHOD IMPLICIT after the START card.
4. Save and close the halcon2_runcontrol.dat file.
5. Copy the halcon.fcs file located in the WS4 directory, and paste it to the same location. Rename the new file to halcon2.fcs.
6. Open halcon2.fcs using a text editor (Notepad), locate the RUNCONTROL section and point it to halcon2_runcontrol.dat file.
7. Save and close the halcon2.fcs file.
8. Submit this job.
9. Report the results in the table on page 5-19.
Nexus® Software, IMPES, 60x40
In this exercise, you will create a Nexus case with 60x40 grids in IMPES formula and compare the results to the base Nexus case with 30x20 grids.
1. Create a new case named halcon3 under the halcon study.
2. Click the SimDataStudio icon ( ) to build the new Nexus model. When prompted, tell the SimDataStudio software that you want to fill your new case by parsing an existing VIP dataset.
• Parse halcon1i.dat and halcon1r.dat files.
3. Under Basic Options in the CORE tab, in the “Grid system” section, check “Use GridGenr grid files” and update the “Grid Definition File” to read your new data, by pointing it to halcon60x40.lgr. Make sure the files under Grid System change to halcon60x40. If any do not, change them manually, using the file selection folder. To ensure the proper fault file is read, click Grid-
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Related Data>Multipliers - Overrides>Connections Transmissibility Modifications. The file under Value should point to halcon60x40.fml. If it does not, change it manually.
4. Under the EXEC tab, open the Well Perforations table, and right-click. Select Import Perforations from an ASCII file. Select halcon60x40.fpf to overwrite the existing perforations.
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5. Scroll through the resulting update and notice that perforation locations (IW, IJ) frequently fall in grid locations not possible with the old 30x20 grid, but reasonable for a 60x40 grid. For example, the last entry in the table refers to a D2 perforation at (39, 26).
Notice, also, that more halcon60x40 perforations (89) were calculated than halcon (83).
6. Generate the new Nexus file.
7. Save changes to the .vds file and exit the SimDataStudio software.
8. Submit this job.
9. Record these findings in the table on page 5-19.
Nexus® Software, IMPLICIT, 60x40
In this exercise, you will create a Nexus case with IMPLICIT formula and compare the result to the base Nexus case with IMPES formula in 60x40 grids. Follow the same procedures that you used for creating the second Nexus case.
1. Create a new case named halcon4 under the halcon study.
2. Open the halcon3.fcs file and save it as halcon4.fcs.
• Locate the RUNCONTROL section in the halcon4.fcs file and change the entry from halcon3_runcontrol.dat to halcon4_runcontrol.dat.
• Save and close halcon4.fcs file.
• Copy the halcon3_runcontrol.dat file located in the WS4\nexus_data directory, and paste it to the same location. Rename the new file to halcon4_runcontrol.dat.
• Open halcon4_runcontrol.dat using Notepad (or text editor of your choice), and add METHOD IMPLICIT after the START card.
• Save and close halcon4_runcontrol.dat file
3. Submit this job.
4. Record the findings in the table on the next page.
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Record your results in the following table for comparison.
Case Name Grid Blocks Time Steps Run Time Job Formulation (seconds) Submitter halcon 30x20 Nexus IMPES halcon1 30x20 VIP IMPES halcon2 30x20 Nexus IMPLICIT halcon3 60x40 Nexus IMPES halcon4 60x40 Nexus IMPLICIT
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Discussion Points
You should now be able to discuss the following questions:
• How does changing the formulation method affect:
— run time?
— memory used?
— timesteps?
• How does changing the grid size affect:
— run time?
— memory used?
— timesteps?
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In this chapter, you will learn some of the features of the SimResults+3D™ software and Nexus View® software. The SimResults+3D software is a Windows-based application for graphing and analyzing the output from simulators, such as the Nexus® software.
Since the SimResults+3D software is the plotting module for both the Nexus software and VIP® programs, those users that have already taken the Introduction to VIP Programs course will already be familiar with it. The Nexus View software, on the other hand, is a new common visualization environment for geological, geophysical, and reservoir models that has been developed for the DecisionSpace® suite of software.
Introduction
In this chapter, you will:
• Learn about the SimResults™ software.
• View results in the SimResults software.
• Plot multiple properties.
• Change display attributes.
• Save a session.
• Plot well constraints.
• View results in the Nexus View software and use the data clip, lighting, color, and fling features.
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About SimResults+3D™ Software
The SimResults+3D software is a Windows-based application for the graphing and analysis of the Nexus and VIP output, and can be split into four sections as shown below:
Menubar
• The menubar and icons control all operations of the application.
• The tree view displays available data for plotting.
• The graph list contains a historical list of all graphs.
• The drawing area displays all graphs.
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Exercise: Viewing Results in SimResults+3D™ Software
Once you have finished running the simulation on a case, use this exercise to start and begin learning the SimResults+3D software.
1. From the Nexus Desktop® software window, select File > Open/Create Study, then select the Visualization study from the WS5 folder.
2. Highlight the halcon case and click the SimResults icon ( ) to launch the module.
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You cannot see a plot yet because you have not selected a property to plot. Notice, however, that the correct case has been automatically loaded.
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3. Expand the tree view to locate the properties associated with well1 (W1).
4. Click and drag the W1 property QOP (Oil Production Rate) from the tree view into the drawing area.
When QOP is selected, a large arrow pointing to the right is highlighted. The arrow changes into a large “Y” when the cursor is over a valid drawing area. When the mouse button is released, the graph of QOP against time is displayed.
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. .
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Plotting Multiple Properties
In the previous steps, you plotted a single trace. This exercise shows you how to plot multiple traces and view the same properties for different wells.
From the SimResults tree view, click and drag the W1 properties CWP (Cumulative Water Production) and CGP (Cumulative Gas Production) onto the same display window as QOP from the previous steps.
All curves are displayed on the same graph, as shown below. Notice how the plot legend (top of window) shows which properties are being plotted at any given time.
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Changing Display Attributes
Removing a Displayed Trace
In the previous steps, you plotted the properties QOP, CWP, and CGP. This exercise shows you how to remove a trace.
1. In the drawing area, double-click directly on the QOP curve. This opens the Line Settings dialog box for this curve.
If Line Settings for the wrong curve opened, use the Next Curve / Previous Curve buttons (<<, >>) to locate the curve QOP.
2. Click Delete at the bottom of the panel.
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WARNING: The current version of SimResults has a bug that impacts this exercise. To work around the bug you must delete all three curves from the current plot and add COP, CWP, and CGP back to the plot, as shown in Step 4.
3. Click OK to close the dialog box.
4. Add curve COP to the display by dragging and dropping as you did with the other properties.
5. Choose New Axis at Left, if requested.
Editing the Plot Title and Legend
This exercise shows you how to modify the title and legend in the plot window.
1. Double-click either the plot title or legend to open the dialog box for modifying settings.
If you can’t see the title, it might be under the legend. To find out, toggle off the legend either by using the Toggle Legend icon, or by selecting Graph > Settings > Toggle Legend from the menubar.
The dialog boxes for modifying title and legends are shown below.
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Changing the Line Type
This exercise shows you how to change the color and type of line used for displayed traces.
1. Double-click the trace for COP.
This displays the Line Settings panel shown below. If it opens for the wrong curve, use the Previous Curve / Next Curve buttons to locate COP.
2. Experiment with the various Plot Type options (Scatter, Line + Scatter, Bar Chart) before resetting the type to Line.
3. Change the line color for COP to Light Green.
4. Use the Previous Curve / Next Curve buttons to change the line color for CGP to Light Red, and CWP to Light Blue.
5. Click OK to close the Line Settings dialog box.
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Changing the Y-Axis
The SimResults software lets you set display attributes for each of the y-axis line and text components in your plots. This exercise shows you how to customize the individual y-axis to match the previously modified curves.
1. In the Drawing area, double-click the Y Axis for COP.
The Y Axis Title dialog box appears.
2. Change the Title Font color to Light Green (to match the COP curve).
3. Change the Font to Comic Sans MS (or whatever you prefer).
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4. Select the Grid Lines tab and turn on the Major Axis, using the default color (Gray) and line width (1).
5. Select the Label Format & Range tab to see the options for changing the property scale.
Experiment with options to see their impact.
6. Click OK to close the Y Axis Title dialog box for COP.
7. Double-click the Y Axis for CGP.
8. Change the color to match the curve (light red).
9. Change the font to match COP.
10. Click OK.
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11. Double-click the Y Axis for CWP.
12. Change the color to match the curve (light blue).
13. Change the font to match COP and CGP.
14. Click OK.
15. Locate the Next Item icon (yellow binoculars) to scroll through the other wells and verify that your changes were propagated to all wells.
Next Item: (New Window)
Note that the Next Item (New Window) icon (blue binoculars) will display the same plot for the next well in your list, but in a separate page within the drawing area. Pages are managed in the Graph List area of the SimResults window.
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Exercise: View Data in Spreadsheet
The SimResults software lets you view data in spreadsheet format.
View Current Data
This exercise shows how to view all of the currently available data in the SimResults software.
1. Highlight Plot branch, right click and select View Current Data.
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2. Click on File > Open and reload the study. Select "All data" and overwrite.
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3. Load the 3D grid with properties from Solution:
4. Now, right-click on the data type name under "Solution" (for example, 1 APR 1997) and select View Current Data from the menu.
Note, the data should be already loaded on 3D grid to be able to view it.
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The Visualization_halcon\Solution\1 APR 1997 window appears.
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View Graph Data
This exercise shows you how to view the data showing in the plot.
1. Highlight the halcon COP CGP CWP plot and select Graph > View Graph Data from the menubar.
A spreadsheet displays the graph data.
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2. To save the data in Clipboard for future use, click .
3. A "Graph Data Copy" window appears. Click OK to close the window.
Now, you can open an Excel file and paste the data.
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Exercise: Create Reports
The SimResults software lets you create reports of the plots you created. This process applies for Microsoft PowerPoint, Word, Excel and HTML documentation.
This exercise shows how to set up this option and create the report.
1. From the menubar, select Tools > Options.
The SimResults Options window appears.
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2. In the General tab, set the Reports Folder by clicking .
3. Set Desktop as the report location and click OK.
4. Click the MS Office tab.
5. Check all three MS Office applications and click .
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6. From the menubar, select Tools > Report > Microsoft Word 11.0.
The Browse For Folder window appears.
7. You can again choose a location to save the report. In this exercise, click OK to accept the setting.
8. A message pops up telling you that the document has created successfully. Click OK.
Now, you should be able to open the report created from your Desktop.
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Saving Sessions in SimResults™ Software
One of the most useful features of the SimResults software is that it includes a powerful macro language called GRF that allows you to save your created graphs as a set of instructions that can be used to create the same graphs at a later time. The SimResults software acts as the interface to creating the set of GRF commands so there is no immediate requirement to learn the details of the GRF language.
This exercise shows you how to capture the current plot in a GRF Session file. It also shows you how the saved page is still available later, and how to retrieve it, even after you quit the SimResults software.
1. From the menubar, select View > Session > View as GRF.
The macro language for the current plot is displayed in its own window.
2. Select File > Save to write a file named cumulatives.grf to your WS5 directory.
3. Select File > Exit to close the GRF Edit window.
4. Select File > Exit to quit the SimResults software.
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5. Launch the SimResults software again by clicking its icon on the application toolbar in the Nexus Desktop window.
6. From the SimResults menubar, select File > Open, and select cumulatives.grf from your WS5 directory.
The plot name appears in the graph list.
7. Double-click the entry for Page #1.
The same plot you created earlier should now be visible.
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2D and 3D View in SimResults™ Software
In previous exercises, plotting using the SimResults software was introduced. Now, you will learn how to view 2D and 3D maps in the SimResults software.
1. Load all data for a case. Select File > Open from the SimResults menubar. When the Open File window appears, open the Visualization.vdb file from WS5 folder.
2. When the VDB Files window appears, check Load all data for this case and click OK.
• Plot, Map (INIT) and/or Map (RECUR) data can be selected or completely loaded.
• Plot data can be selectively loaded By Class and by their respective members (that is, wells).
• Map (INIT) data can be selectively loaded By Vector.
• Map (RECUR) data can be selectively loaded By Vector and By Timestep.
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.
3. When prompted, choose to overwrite the name currently in use.
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This loads all the available data for the case, including Grid, Init and Solution data. Expand the branches as needed.
Since the SimResults software loads all data into memory, the loading process can take some time for big models, and can create a limitation on the size of data that can be loaded. However, once the data is loaded, visualization of the data and changes on its display is immediate. Now, SR has the HPG option for on-demand data loading.
4. Drag ROOT 30x20x9 (under Grid) to the drawing area, then release it.
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You will see a 3D grid plot.
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5. Under Solution, drag P from April 1, 1997 to the grid plot and release it. You should have a plot like the following:
6. Hold and drag the left mouse button to rotate the plot.
7. Hold and drag the right mouse button to zoom in or out, or use the zoom icons ( ) from the Application toolbar.
8. Left-click any cell to check that cell’s I, J, K location and pressure value at the bottom of the plot.
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9. To expand the cells, click the Grid > Grid Settings icon ( ) from the menu bar and select Scale Factor/Explode Settings. A Grid dialog box appears. Set Z Scale to 4. Since Auto Apply is checked as the default, you will see the change.To set opacity, select Grid >
Grid Settings > Transparency & Lighting from the menubar, or click anywhere in the plot and choose Transparency & Lighting
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from the popup window.
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10. To clip the grid Grid > Grid Settings icon ( ) from the menu bar and Fence Plots. Change the settings as needed.
11. To view a single layer, select Grid > Single Layer 3D from the menubar, or click the Single Layer 3D icon ( ) in the bottom of the window to activate the layer select settings.
12. Set the transparency back to 0%.
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13. Click and select Layer 4 to view.
14. To view in ternary mode, click the Ternary Mode icon ( ).
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15. Unclip the grid, and display all layers in 3D.
16. To animate the display so that the model automatically cycles through its timesteps, set the last date as the last Timestep to be displayed, and click the Play icon ( ) to start the animation. Click the Continuous Play icon ( )to activate continuous play, and increase the display speed as needed.
17. To view 2D, select Grid > 2D View, or click the 2D View icon ( ) in the bottom of the window.
18. Drag any variable under Init or Solution to the plot and release the mouse.
Note that Init is initialization data and Solution is simulation data.
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Introduction to Nexus View® Software
The Nexus View software is a visualization environment for geological, geophysical, and reservoir models. The Nexus View software consists of two main components: 3D Viewer and Data Selector.
The 3D Viewer contains:
• Menu options and controls, which allow you to manage sessions, manipulate the view, launch other applications, access tools, and access the online Help system
• Toolbars below the menubar containing icons that allow you to quickly access many of the menu options
• The workspace, which displays a hierarchy of the data objects in the working dataset organized by object type
• The 3D view area, which displays the objects in the scene
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In this version, there are now two tabs to the side of the display. One is labeled Data Selector and the other is labeled Display Settings. To access the Data Selector, you must click on the appropriate tab. The data selector information will be shown to the left of the 3D view area. The same thing is true for the display settings that used to be shown as part of the Data Selector window.
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Exercise: View the Nexus® Software Model in Nexus View® Software
Launch Nexus View® Software
You can access Nexus View software by clicking the Nexus View icon ( ) from the toolbar in the Nexus Desktop window.
1. In the Nexus Desktop window, make sure the working case halcon is highlighted.
2. Click the Nexus View icon ( ).
One window will appear with two tabs (Display Setting and Data Selector) at the upper left corner.
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.
Data Selector
The Project tree option allows you to set the rendering controls for display of 3D grids (VDBs with grids created by Nexus or VIP, Rescue block units, and Eclipse results files).
1. Project accesses a drop-down containing the names of all 3D grids that have been loaded. Click the desired 3D grid to select it.
By default, the working case Visulization.vdb is displayed.
Clicking ( ) will open up a dialog box which you can use to browse to and select the 3D grid that you want to load.
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Clicking ( ) will open up the Unload 3D Grid dialog box. The currently selected 3D grid is listed. When you click OK, the 3D grid is unloaded and removed from the Working Dataset.
The Active Project panel of the Reservoir Model tab allows you to select the data type to be displayed.
The Model tree lists the reservoir model by name and contains nodes for 3D Grids, 3D Grid Slices, 3D Isosurfaces, Properties, Wells, Streamlines, Regions, Faults, and Surface Networks, which you can use to access specific data objects in the Data Selection panel.
The Data Selection panel allows you to select specific data objects for display and advanced display options.
Notice that the property displayed by default is recurrent SO (oil saturation).
You can also view initialization data by selecting INIT.
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2. To view dual properties, select Dual and the properties desired.
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3. To view Ternary properties, select Ternary and the properties desired.
4. Set recurrent SO as the objective data for view.
Now, you will manipulate the view by changing the settings in the Display tab.
• Color mode allows you to set the color display. The display can be Colormap or Filled Contours.
• Colormap maps the color to a data value. Use the drop-down Colormap list to select from several preset colormaps.
• Filled Contours displays the gridded contours as color-filled surfaces. The result is a display that resembles a smoothed version of the horizon that was sampled when the grid was created.
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• Color Extremes allows you to limit the range to which the colormap is applied. Adjust the min and max using either the slider bar or the text boxes. Data outside this range will be colored using the extreme values of the colormap.
• Colormap scaling allows you to set the scale type. The scale type can be Linear or Log (base 10 logarithm). The Color Editor, when displayed, will display the current colormap scale.
• Render mode allows you to set how the image will be rendered. This can be Etched, Solid, or Wireframe.
• Show grid outline displays the outline of the grid. This is useful when the grid is highly filtered and the original shape of the grid is no longer obvious.
• Show grid/LGR names displays the names of the selected 3D grids and LGRs.
On the Nexus View window you have the following:
• Z thicken allows you to set the scale value. The scale value can range from 0 to 20. When non-zero, it applies a proportional scaling to the z thickness of all reservoir objects in the view. Note that horizontal grid slices cannot be z-thickened.
• Transparency allows you to specify a level of overall transparency for the displayed object. Dragging the slider to the right increases the transparency. Dragging it to the left decreases transparency.
• Clip Grid ( ) launches the Clip Grid dialog box. Each grid in the model can be clipped individually by selecting the appropriate parent grid in the Grid Name selection box.
When clipping a parent grid, use the Clip Children option to clip the local grid refinements (or child grids) that belong to the parent grid. Use the Grid Clip (cell) sliders to specify a min and max for the columns (I), rows (J), and layers (K) to be displayed. Use the Grid Step (cell) sliders to specify a grid step. Use the Reset option to restore the active grid to the original values, or click Reset All to reset all previously clipped grids to their original values.
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You can also create fence diagrams with this panel by selecting Use Fence-Style Clipping/Stepping. Fence diagrams are useful for creating different effects by removing parts of the model.
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• Cutting Planes ( ) launches the Cutting Planes dialog box, which you can use to define arbitrary slices through the model, in both the X and Y directions, by interactively positioning planes that are superimposed on the displayed model. The control of the position is a combination of translation and rotation of the plane. By default, the cutting plane removes all the cells on one side of the cutting plane. Click Reset to restore the original values.
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• Time Step panel displays when you select RECUR class data or wells as the property to be displayed. Time Step changes the timestep of the rendered object. Time in Days is the number of days from the simulation start date.
3D Viewer
The menu options at the top of the 3D Viewer provide drop-down menus that allow you to manage sessions, manipulate the view, launch other applications, access tools, and access the online Help system. The main menu options are:
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• File accesses options for loading 3D grids, managing sessions, and printing.
• View accesses options for managing your view. Select View > Workspace. The Workspace is displayed. Expand the tree if needed.
• Launch allows you to launch other applications from the Nexus View software.
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• Tools accesses specialized tools that can be used with the Nexus View software.
• Window accesses options for managing tabs/tiles for multiple scenes.
• Help accesses the Nexus View online help, release notes, and build information.
• Options accesses the startup preferences and advanced models parameters.
The basic 3D Viewer window contains eight toolbars, grouped according to function.
• Print toolbar:
Icon Corresponding Function Menu Option
File > Print Sends a snapshot of the 3D view to a printer.
File > Print Preview Allows you to preview the scene that will be printed.
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• View control toolbar:
Icon Corresponding Function Menu Option
View > New Depth Scene Adds a new empty depth scene to the 3D view. You can then manipulate the scene to create a different view of the same scene.
View > Clone View Clones the selected scene and adds it as a new scene.
View > Inventory Manager Brings up the Inventory Manager, which lists all objects loaded in the current session.
View > Illumination Controls Toggles lights on or off in the 3D view.
View > Full Screen Activates Full Screen mode.
View > Fling Using Mouse Allows you to continuously rotate the scene.
1. Go to Data Selector, in the Data Objects tab, choose INIT to view the recurrent data, and click PV as the property.
2. Go back to 3D Viewer and click ( ).
The Inventory Manager window appears. Notice that only the initial PV is displayed in the 3D Viewer now.
3. Check item 1.
The recurrent SO is also displayed in the 3D Viewer.
4. Uncheck item 2 to display the recurrent SO only.
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• Cursor mode toolbar:
Icon Corresponding Menu Option Function
View > Cursor mode > Center of Interest Activates Center of Interest mode, allowing you to select the point about which the scene is positioned.
View > Cursor mode > Measure distance Activates Measure Distance mode, allowing you to measure the distance between two points.
• View main toolbar:
Icon Corresponding Menu Option Function
View > Set Home Sets the current scene position as the home position. Note : you can also set home using Shift-Home on your keyboard.
View > Go Home Returns the scene to the home position. Note : you can also return to the home position by pressing Home on your keyboard.
View > View Selected Centers and zooms the 3D view on the selected object(s).
View > View All Centers and zooms the 3D view to see the entire scene.
View > 3D View Properties Opens the 3D View Properties dialog box.
View > View Mode > Perspective Changes the scene to a perspective view.
View > View Mode > Orthographic Changes the scene to an orthographic view.
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• Zoom/Scale toolbar:
Icon Function
Zoom in (slide to the right) or out (slide to the left) on the scene.
Stretch or compress the Z scale (z to x,y ratio) of the scene.
5. Zoom in or out to your desired view and set the ZScale as 4.
• VCR toolbar provides a set of VCR controls which appear below the 3D display area. You can use these controls to animate reservoir model 3D grid data (.vdb) containing RECUR data through timesteps.
Note
To check the timestep, go to the Time Step panel in Data Selector.
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• Inquiry Mode toolbar:
Icon Function
Accesses detailed property information on a selected cell in a 3D grid.
Allows you to display only cells within a user-picked polygon or streamlines between two reservoir wells.
Allows you to display reservoir well allocation factors data for selected wells.
6. Click the Grid Inquire icon ( ), then click a cell in the 3D grid. A box opens with information on the grid and cell.
You can select any property to display from the Values selection list and then click a grid cell. The selected cell highlights within the display and the corresponding property values are shown.
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• Advanced Tools toolbar:
Icon Function
Launches the Define Grid Slices tool. This tool enables you to define grid slices, animate them through the grid, and save them for display in subsequent sessions.
Launches the Create Isosurfaces tool. This tool enables you create surfaces that share a single property value. For example, specifying a porosity value of .4 displays a surface consisting of all the cells in the grid that have a porosity value of .4. You can save the isosurfaces for display in subsequent sessions.
Launches the Display Flow Vectors tool. This tool enables you display velocity flow vector data for gas, oil, and water. Note : This tool functions only with VIP velocity data that you have generated using the VIP FLOWVEC, FLOWO, FLOWG, and FLOWW keywords.
Launches a Well Plotting dialog box. This dialog box provides instructions on how to generate a well line plot – that is, click the well boreholes for which you want to view line plots, then click OK.
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7. Click the ( ) icon to open the Define Grid Slices window.
8. Click two points in the grid map.
A white line appears.
9. Click Apply.
A slice appears.
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10. Check Convert polyline to plane.
The Slicing Plane is activated. Move the bar or click the arrows to transfer the slice. Try other options.
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11. Click the ( ) icon to open the Create isosurfaces window. Set the value to 0.3 and click Apply.
12. Click ( ) to open up the Display Flow Vectors window.
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13. Check all Oil, Water and Gas, set the Arrow Scaling and Arrow Max Size as 2, and click Apply.
The flow vectors are displayed in the 3D Viewer. Note that green vectors are oil, red vectors are gas and blue vectors are water.
14. Click ( ) to open the Well Plotting window.
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15. Click the wellbore of the well for which you want to display data.
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16. Click OK in the Well Plotting dialog box. Line plot will display for the well that you clicked on.
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Discussion Points
You should now be able to answer the following questions:
• What is the SimResults software?
• How do you add new well properties to an existing plot? How do you remove them?
• What visual plot properties can be altered?
• What is the Nexus View software?
• How do you load a 3D grid into the Nexus View software for visualization?
• What are instances in which you might use the SimResults software instead of the Nexus View software? Why?
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5-60 Nexus® Software R5000.4.8 Basic Reservoir Simulation Chapter 6 Historical Production Data and History Matching
This workflow shows how to use the SimDataStudio™ (SDS) software to prepare historical data for use in a simulation and apply several history matching methods.
Introduction
In this chapter, you will learn how to:
• Generate well traces and perforations using Perforation Wizard.
• Load production data.
• Generate well constraints by production data.
• Adjust data for history matching:
— Add an aquifer
— Adjust fault multipliers.
— Adjust WOC.
— Adjust permeabilities.
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Introduction to the Perforation Wizard
The Perforation Wizard is a SimDataStudio tool that helps you directly edit perforation data and adjust geological layers and faults to the simulation grid.
The Perforation Wizard lets you load well trajectory and perforation data from:
• An ASCII text file (The format is similar to those output by most applications, including the Wellbore Planner™ software.)
• A GRIDGENR (*.gtf) file
• The OpenWorks interface is not currently supported.
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Exercise: Create a Nexus® Software Model
In the following exercise, you will create a new case and use the SimDataStudio software to import production history, and load well trajectory and perforations.
Create a New Case
1. Create a new study in WS6 directory, and name it history. Name the case history1.
2. Highlight the history1 case and click the SimDataStudio icon ( ).
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3. Select Create a new case by parsing an existing VIP data set. Parse the CORE file from halcon1i.dat. Do not parse anything into the EXEC file.
4. Click OK.
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Exercise: Load Well Trajectory and Perforation
To load the well trajectory and the perforations, the simulation grid must exist in a VDB. The grid may come from existing CALC class data, if the geomodel is the same as the simulation model, or it may be created by initializing the simulation model. Once the grid exists in the VDB the Perforation Wizard can be used to populate the Well Perforations table and the Well Names and Locations table.
In this exercise you will create the grid by initializing a Nexus model, using the data that you just imported into SimDataStudio.
1. Select Simulation Data > Generate Simulator Data File > Nexus initialization files from the SimDataStudio menubar.
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2. When the Nexus Data Set Generation … window appears, use the default name for your nexus case file (history1.fcs) and verify that you have not violated any data entry restrictions. Notice that there is no recurrent data at this time.
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3. Click Generate to generate the files, review the .fcs file and notice the new keyword “INITIALIZE_ONLY”.
4. Create a Nexus Job and submit initialization job. When the job is complete, use Nexus View to verify the VDB study and case contains the simulation grid with INIT class data, Note that RECUR class data will also be available.
5. On the EXEC tab in the SimDataStudio software, double-click Well Names and Locations or Well Perforations to activate the Perforation Wizard icon ( ). Click the icon to start the wizard.
6. First, you will need to select a grid from a .vdb file.
•Click to point to the history.vdb in the WS6 folder.
• The history1 case will display automatically.
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• If you have multiple cases in this .vdb, click to select the case you are interested in.
7. When you finish selecting the simulation grid, click Next to select the well trajectory text file.
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8. Click the icon to insert a new file.
9. Click the icon to select the well trajectory file.
10. When the Open window appears, set the file type as *.gtf and select the file halcon_wells.gtf.
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11. Click Open.
The filename and path will display.
12. Click to view this .gtf file.
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Note:
As an alternative to the .gtf format, column-based ASCII files have also been provided. These files are halcon_well_trace.data for the well trace data and halcon_well_events.data for the perforation data.
13. Click Next.
A message window appears to tell you that there were nine wells found without any perforation data, and that perforations over all the well trace intersections in the reservoir will be assumed.
14. Click OK.
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You are prompted that there was no marker data, and that all perforations were calculated from the intersection of well trajectories in the simulation grid.
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15. Click to view the intervals.
16. Click the icon to view perforations with the 3DView™ software.
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17. When the 3DView software opens, select Grid > Display Options to set Grid Face Opacity to 0.2, then click OK.
18. Use Wells > Well Options to toggle on Show Well Perfs, then click OK.
19. Zoom in to see the calculated perforations.
20. Exit the 3DView software to return to the Perforation Wizard, then click Next.
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21. For the Final Step, accept the default settings and click Finish to export perforations to the SimDataStudio software.
22. In the SimDataStudio software, note the populated Wells Names and Locations table and Well Perforations table.
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23. In this exercise, well W8 should be only perforated in the first layer.
• Double-click the Well Perforations option.
• Right-click the last row and select "Delete Selected Perforations" for Well W8.
Now, 83 perforations are displayed.
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Exercise: Reviewing and Importing the History Data
This exercise shows how to import the history data into the SimDataStudio software so that it will be available for viewing and editing, for use in generating well constraints, and an observed data file.
A file called “halcon_history.txt” was included in your WS6 directory on your training workstation. This file contains 560 production history records for all the wells you will import. Open this file using your text editor of choice to examine its contents.
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1. In the SimDataStudio software, double-click the Production Data entry on the tree menu to open it in the panel on the right side of the screen.
The Production Data table (currently empty) opens.
2. Select Production Data > Import Production Data (or right- click in the Production Data table and select Import... from the dialog box that appears).
3. As shown in the following, select halcon_history.txt as the file to be imported.
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4. Click the Open button to begin reading the data file.
This opens Step 1 of the Import Production Data Wizard.
The wizard gives you a preview of the production data in the file, with horizontal and vertical scrollbars so you can review the data.
Date Format Once the data is imported and interpreted, you can easily display the dates in U.S. format (month-day- year), Euro format (day-month-year) or as days since the beginning of the first production interval.
Number of As shown in the message at the top of this panel, the Data Columns SimDataStudio software automatically determined that there are eight columns of data in this file, which is the correct number.
Separator,Delimiter As shown in the message at the top of this panel, the SimDataStudio software automatically determines that the data is separated by tabs, which is correct.
Units of Data in File This shows your default units as selected in the User Options dialog box. Change if necessary.
5. Review the data and change the data options as shown in the following.
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6. Click the Next button to continue to the next panel of the wizard.
For each column of data in the file, the SimDataStudio software attempts to identify the column heading and data type. This page of the wizard shows the results of this interpretation process, and lets you adjust the formatting selections column by column.
7. Make changes as necessary, using the table below as a guideline:
Col. Heading in Original File Selections to Make in Wizard
Wellid Name: Well ID
Oil_vol Name: Oil Production Units: Volume - MSTB
Water_vol Name: Water Production Units: Volume - MSTB
Gas_vol Name: Gas Production Units: Volume - MMSCF
Waterinj_vol Name: Water Injection Units: Volume - MSTB
Gasinj_vol Name: Gas Injection Units: Volume - MMSCF
Pressuremon Name: Bottom-hole Pressure Units: Pressure - PSIA
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8. Click the Next button to continue to the next panel of the wizard.
9. The SimDataStudio software lets you adjust the date range for the imported data and the wells to be imported. To import all wells, check the Import All Wells checkbox.
10. Click the Finish button at the bottom of the wizard.
The SimDataStudio software will read the production data into the worksheet area of the display.
The Production Data worksheet gives you complete functionality to review and edit production data on the screen. Use the horizontal and vertical scrollbars to view all columns and rows.
Notice that you can edit individual values, and add or delete rows.
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Reviewing the Charts
1. Scroll to the far right side of the Production Data worksheet to bring charts of the imported data into view.
2. To zoom in or out for a better view, use the icons on the toolbar, or the related options on the View menu.
Icon Purpose Related View Menu Option
Zoom in on worksheet and charts View > Zoom In (enlarge the perspective).
Zoom out on worksheet and charts View > Zoom Out (shrink the perspective).
Return to original size. View > Original Size
Each time you select a zoom in/out function, it enlarges/shrinks both the worksheet and the related production charts. Selecting Original Size returns the worksheet and charts to their original size.
Averaging the Data (Required)
Before generating type and constraints from production data, you may want to use the data averaging option to average your production data over fixed intervals or varying intervals defined within date ranges. This process insures data values are not misapplied to the wrong intervals during the Nexus® software reservoir simulation run.
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Two procedures are included on the following pages. The first procedure shows how to accomplish the data averaging process. The second procedure shows how to interactively adjust the results by using the mouse and charts.
Setting Up and Performing the Averaging 1. Select Production Data > Average Production Data from the SimDataStudio menubar (or right-click and select from the resulting popup menu).
• This displays the Data List Selection panel. This panel shows the Start Date and End Date for the production data.
2. Select a Frequency for averaging, and see the resulting interval dates in the Date List.
You can use the scroll arrows to increment or decrement the Frequency value, and watch how this dynamically changes the Date List. You can average data over any interval desired, including the current interval.
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3. Set the Frequency to 3 months and click OK.
Do not average over important dates.
The SimDataStudio software uses this data when generating the simulation data file. Averaging should not skip important dates such as a well shut-in. You can manually change any value in the worksheet and the data will be re-averaged automatically.
Interactively Adjusting Averaged Data You can view averaged data in the charts to the right of the Production Data worksheet, and interactively adjust the averaged data intervals.
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If you do not see the vertical grid lines in the chart, select Production Data > Properties, then click the Production Charts tab and check the Averaged Interval Grid Lines checkbox. Click OK to close the Production Data Properties window. (You cannot edit the production charts until this window is closed.)
Changing production chart line colors
Note that you can change the production chart line colors by selecting Production Data > Properties > Production Charts > Pick Color. Once changed, the colors you select become the new default.
You can drag these grid lines left or right to interactively adjust the averaging interval.
To begin this process:
1. Move the mouse to the top of the grid line until you see a large black vertical arrow.
2. Hold down the left mouse button. The arrow turns into a white horizontal double-arrow. Hold the mouse as you drag the grid line left or right. The axis annotation changes automatically to match the current grid line position.
3. Release the mouse when the grid line is at the desired position.
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Generating Date Records Automatically
The SimDataStudio software lets you generate a series of date records automatically by specifying a start and end date, the frequency of DATE cards, and a frequency for each of the key output cards.
Note
The simulation END date will automatically be set using the last date from the imported monthly production volumes. If a different END date is desired, double- click Utility Data in the tree menu and set the desired date. Even if no change is desired, it is a good idea to double-click Utility Data and make sure the expected date was set.
1. Double-click the Output Options option in the tree menu to the left of the worksheet display area.
The worksheet displays the previously defined Start and End dates.
This display lets you set up a list of Run Dates, then designate various events that will occur on those dates, such as:
• PRINT options – reports printed on certain dates
• MAP options – map records generated on certain dates for use by the 3D View/Nexus View® software
• PLOT options – plot records generated on certain dates for use by the SimResults™ software
• RESTART – restart records captured on certain dates for use in starting new simulations at different dates (use carefully, since these generate large output files that can quickly fill up your hard drive)
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2. Right-click in the worksheet area to select Generate New Output Date List.
3. Define the Print, Plot, and Map options, as shown in the following, for 3-month intervals. Write a Restart every 2 years.
4. Click OK.
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The date list is generated automatically, and looks similar to the following:
Generating Well Constraints
Once production data is imported, you can use another wizard to generate well types and constraints.
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1. Double-click the Well Constraints option.
2. To run the wizard, from the menubar select Production Data > Generate Well Types and Constraints from Production Data.
Primarily, this panel shows the start and end dates of both your simulation data and historical production data. It could also point out a variety of problems that might still exist with your data, such as the fact that your production data may still need averaging.
If you need to change any of the dates shown on this panel, you cannot correct them here. You must cancel and change the dates using the other EXEC options previously discussed.
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3. To continue, click the Next button at the bottom of the wizard.
The final panel of the wizard is displayed.
This panel shows wells defined for the simulation, and lets you control how the observed data file will be generated.
4. Toggle on the from raw production data option in the Observed Data File panel. Accept the default OBS filename as history1_obs.csv, and make sure write it to your WS6 directory.
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5. Click Finish to populate the Well Constraints table.
Notice that there is now a history.obs.csv tab where you can check the historical data.
Generating the Nexus® Software File Now that you have finished setting up your data in the SimDataStudio software, you are ready to generate the Nexus model.
1. Select File > Save Case or click the Save icon ( ) to save your SimDataStudio work so far.
This saves a .vds file.
2. Select Simulation Data > Generate Simulator Data File > Nexus files from the SimDataStudio menubar.
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From here you can specify names for your files (history1.fcs and history.vdb) and verify that you have not violated any data entry restrictions.
3. Click Generate.
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Simulate the Model in Nexus® Software
1. Highlight the "history1 Nexus Simulation" in the Nexus and VIP Simulation window.
2. Assign the observed data in the job submit window. This will load the observed data into halcon1 case folder inside halcon.vdb.
3. Submit the job.
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Using SimResults™ Software to Examine Results
Previously, the observed data was exported from the SimDataStudio software and imported through the SimConvert software. If you now use the SimResults software to examine the results, you can see the simulated results and the observed data side-by-side on the same graph. This makes it easy to visually compare simulated reservoir conditions to real-world conditions, to see how far your model deviates from reality. If there is a wide gap, you can adjust your model parameters, rerun the simulation, and continue comparing observed/simulated data in an iterative process until you see a fairly good match on your observed properties.
The following exercise shows the basic workflow of this iterative process. Take a few minutes to work through this exercise so that you can learn what a history-matching comparison is all about.
1. Since the historical data is imported to history.vdb, you need to reload this study. In the Nexus Desktop window, highlight history.vdb and click to reload it.
The Observed Data option is checked in the Viewer panel, which means you can view it in the SimResults software.
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2. Click to launch the SimResults software. In the data tree, notice that your history1 case shows a folder as Observed data.
Expand the data tree as needed.
3. Create a plot showing QOP for well W1.
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4. Open the Observed branch, and drag QOPH to add the historical oil production rate data for the same well to the same plot. (When prompted, select the same Y Axis as QOP.)
Notice that simulated data is represented by solid lines and the historical (observed) data is represented by symbols. The legend shows which symbols correspond to which properties.
5. Toggle on the Automatically add observed data line to graph icon ( ) or select it from the menubar under Graph > Settings.
The blue cross in this icon will turn to red when you activate it.
6. Create a second plot comparing simulated water production rate (QWP) with historical rate (QWPH).
7. Drag QWP into the drawing area. Note that the simulated and historical data are plotted simultaneously.
8. Use the Next Item icon ( ) on the SimDataStudio toolbar to cycle through the wells and observe the differences for each.
9. Create a third plot comparing simulated gas-oil ratio (GOR) with historical gas-oil ratio (GORH).
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10. Create a fourth plot comparing simulated bottomhole pressure (BHP) with historical bottomhole pressure (BHPH).
You may want to have those four plots in one window.
11. Make sure the Automatically add observed data line to graph icon is activated.
12. Create a plot showing QOP for well W1.
13. Click the arrow after the icon and select 4 Graphs.
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14. Drag QWP, BHP, and GOR to the empty area.
You will have a plot like this:
15. Create additional plots comparing simulated versus historical numbers for other properties of interest.
16. Minimize SimResults but keep it open with the history1 case loaded.
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History Matching
Up to this point, you have imported extensive production history data to use with your current model. This observed data is a literal record of how the reservoir you are trying to model actually behaved over a period of time. If your simulation model is representative, then it should match the observed data reasonably well.
Any gap between actual results and simulated results indicates a need for fine-tuning of your simulation model, making changes consistent with model uncertainty. The process of comparing observed data and simulated data is called “history matching.”
The following list shows observed quantities and adjustable reservoir parameters normally involved in history matching1:
Observed Quantities: • Pressure • Water/oil ratio (WOR) • Gas/oil ratio (GOR) • Water/gas ratio (WGR) • Water and gas arrival times • Fluid saturations
Adjustable Model Parameters: • Aquifer properties (transmissibility and storage) • Reservoir kh (permeability-thickness product) • Relative permeability/capillary pressure • Reservoir porosity/thickness • Structural definition • Rock compressibility • Oil and gas properties • WOC and GOC • Water properties
1. Suggested by Mattax and Dalton, “Reservoir Simulation” SPE Monograph Vol. 13, 1990.
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Adjusting the Data
Modifying Property Data
One technique for fine-tuning is to adjust reservoir parameters normally involved in history-matching properties, such as porosity, pore volume, or transmissibility in key gridblocks.
Here are several ways to do this in the SimDataStudio software:
• Physical Property Array modifications lets you modify physical properties (including porosity, permeability, and rock compressibility) by overwriting array values with values from an Include file, applying a constant to existing array values over some user-defined array section, or replacing array values over some array section.
In this example, the array of permeability in X direction is defined by an Include file. Then, the array is multiplied by a factor of 1.8 for a specific range of gridblocks. The gridblock range being modified includes gridblocks 8 through 10 in the I direction, gridblocks 4 through 6 in the J direction, and gridblock 1 in the K direction. The math operator used above is performing multiplication (*), but you could just as easily add (+), subtract (-), divide (/), or set a specific value (=).
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• Multipliers override lets you modify transmissibilities by overwriting their values or their multipliers from an include file, or over some user-defined array section.
This example shows overwriting a group of transmissibility multipliers in the X and Y directions. Here, for all gridblocks in the specified range (I=6, J=7, K=1 to 9), all the X direction transmissibilities are multiplied by 0.2. For all gridblocks in the specified range (I=6 to 8, J=9, K=1 to 9), all the Y direction transmissibilities are multiplied by 0.2. MINUS indicates that the modification applies to the gridblock face in the minus direction.
Understanding Aquifers
Within the Nexus application, boundary flux is handled by including source/sink terms in the interblock flow equations for edge blocks. The outer boundaries of the grid are normally treated as sealing barriers to flow. This option lets you fine-tune a model by using an aquifer influence to represent a surrounding body of water.
All the data for an aquifer method is input in a single file in the AQUIFER_FILES section as follows:
AQUIFER_FILES AQUIFER method 1 filename1 AQUIFER method 2 filename2 ....
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The aquifer method (if any) to be used by each cell is specified in the PROPERTY_FILES section of the case file using the AQCONN keyword (see the “Aquifer Connection” section of this document). By default, no cells are connected to any aquifer. There are two reports that may be generated to track results of aquifer influx: the first is a summary report given by an aquifer; the second is a detailed influx report given by a grid in which individual cell pressures and influx data are provided. See the “Output” section of this document and the keywords AQUIFERS and AQUIFERSFILE for information on how to generate these reports.
In the SimDataStudio software, you can define aquifers through the CORE > Aquifer Data option.
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Carter-Tracy Method The Carter-Tracy method provides good approximations to the Van Everdingen and Hurst analytical solutions for influx. A radial aquifer geometry is assumed as shown below. The aquifer and the reservoir communicate through the boundary AB. The water influx from the aquifer into the reservoir is the response to pressure changes at this boundary.
The following example shows how this aquifer type is defined in the SimDataStudio software.
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The value under BINF is, as defined by Carter-Tracy, rb/psia (cm/kPa). 2 2c hr s binf = ------t e - 1
where:
average porosity of the aquifer expressed as a fraction
ct = total compressibility of the fluid and rock in the aquifer, 1/psia (1/kPa)
h = net thickness of the aquifer, ft (m)
re = radius to the perimeter of the reservoir, ft (m) (The boundary between the reservoir and the aquifer.)
s = fraction of a circle that the boundary between the reservoir and the aquifer completes
= 5.6146 for conventional units; 1.0 for metric units
The value under TC is used to convert time to dimensionless time, 1/day. k tc = ------2 2 ctd
where:
2 = 0.006328 for conventional units; 8.527x10-5 for metric units.
k = average permeability of the aquifer, mD (mD)
= average viscosity of the fluid contained in the aquifer, cp (cp)
d = re as described above for radial aquifers (length of the aquifer, ft (m) for linear aquifers)
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These values for B1 and TC can also be computed for you based on your inputs of aquifer properties and geometry. Click the Calculate B1 and TC button to open this worksheet.
The range of gridblocks affected is specified after the WINDOW keyword, and a scale factor is used to allocate the total aquifer influx/efflux among the gridblocks attached to the aquifer. These are normalized within the program, so values have only relative meaning. They will usually reflect the cross-sectional area times the permeability of the gridblock faces attached to the aquifer.
Fetkovich Method The Fetkovich aquifer model is a more direct computational method of performing water influx calculations. In this approach, the flow of aquifer water into a hydrocarbon reservoir is modeled in precisely the same way as the flow of oil from a reservoir into a well.
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The Fetkovich method uses a pseudo steady-state aquifer productivity index and an aquifer material balance to represent the system.
The value under PI is the aquifer productivity index in rb/day/psi (m3/day/kPa), which is the total influx rate per day per unit pressure difference. When calculating pi for radial flow, the formula is:
7.08kh pi = ------ re ln---- – 3 ro
When calculating pi for linear flow, the formula is:
kbh pi = ------4 d
where:
k = average permeability of the aquifer, md
h = net thickness of the aquifer, ft (m)
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re = radius to the perimeter of the reservoir, ft (m). (The boundary between the reservoir and the aquifer.)
ro = radius to the perimeter of the aquifer, ft (m)
3 = 0.75 for no-flow outer boundary; 0 for constant pressure outer boundary.
4 = 3.381 for no-flow outer boundary; 1.127 for constant pressure outer boundary.
b = width of the linear aquifer, ft (m)
= average viscosity of the fluid contained in the aquifer, cp (cp)
d = re as described above for radial aquifers (Length of the aquifer, ft (m) for linear aquifers.)
The range of gridblocks affected is specified after the WINDOW keyword, and a scale factor is used to allocate the total aquifer influx/efflux among the gridblocks attached to the aquifer. These are normalized within the program, so values have only relative meaning. They will usually reflect the cross-sectional area times the permeability of the gridblock faces attached to the aquifer.
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Preparing for History Matching
Once you have analyzed the results of your simulation and how they compare to the real-world observed data, you should have noticed the following:
• There are wide differences in BHP and water production.
• Oil production seems to have a satisfactory match.
• The GOR match worsens after pressure is depleted below the bubble point.
Think about the changes that need to be done to the model in order to improve the history match. Load and manipulate the model in the Nexus View software, as shown in the previous chapter, to help you determine the following:
• Do you need pressure support in the field? If so, which area or wells need it? Where can you get pressure support from?
• Are there any wells cutting too much water? If there are, how can you prevent this?
• Are there any faults or flow barriers in the field? Where are they located? Are they sealing? Should they be sealing?
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Results of the Model Visualization
After you have analyzed the results of your simulation and determined the appropriate adjustments for the model, these changes must be implemented.
The first issue you should have spotted is that there was too much gas and not enough water, and that the reservoir is dropping below the bubble point although the observed data is not. This indicates that the simulator is not adequately modeling pressure support in the reservoir, since GOR should be constant whenever the simulation remains above the bubble point pressure. In other words, the steady drop in pressure over time is obviously causing the oil to drop below the bubble point pressure, which in turn is causing free gas to be produced in the field at a level significantly above the consistently low level of gas shown in the observed data.
In order to solve the pressure support issue, the following might be possible solutions for the problem:
• Increase aquifer strength and/or transmissibility.
• Increase the pore volume for the aquifer region by increasing the porosity or coarsen the gridblocks.
Once you decide on an appropriate action, take the action and then rerun the simulation. Repeat this entire procedure as often as needed to produce a good match. You must plot the results in the SimResults software, analyze the quality of the match, decide on more corrective action, take the action, then rerun the model.
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Exercise: Modeling an Aquifer
One of the possible solutions to solve the pressure support issue is to define an analytical aquifer connected to the perimeter of the model to provide pressure support. A clue may lie in the fact that there is an aquifer surrounding the reservoir along its southeast edges.
1. Use the Nexus View software to help you determine which area of the field needs support (that is, find out the range of gridblocks where you will be defining the aquifer).
2. Create a new case named history2 under the history study.
3. Except the aquifer data, all the input data are identical in history1 and history2 cases, therefore, to save time, it's easier to add aquifer data to histry1.vds and save it as history2.vds as following:
• Make sure case history1 is still the working case by highlighting it. Open SimDataStudio if it has been closed.
• In the SimDataStudio software, select File > Save Case As and save it as history2.vds.
• Double-click Aquifer on the CORE tab and accept the default method as Carter-Tracy.
•Click to calculate BAQ and TC.
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• Set the parameters as follows:
• Define the connections.
Hint
Right-click the header to add or remove a row.
4. Select Simulation Data > Generate Simulator Data File > Nexus files from the menubar to generate history2.fcs.
5. Save and exit the SimDataStudio software.
6. In the Nexus Desktop window, make sure history2 is highlighted.
7. Create a new Nexus simulation job by clicking .
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8. Make sure history2.fcs is the FCS File.
9. Run the simulation and see if you can improve the history match.
10. Load the history2 results into the open SimResults session and add the history2 curves to the existing history1 plots. What is the primary impact of adding the aquifer?
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Adjust Fault Multipliers
At this point in the history match, you should have improved the overall pressure match, but certain details will still not be in agreement. Careful analysis of well pairs that straddle faults may lead you to the conclusion that the faults are, at least partially, sealing. In Nexus, fault sealing factors are applied by using tranmissibility multipliers, or MULT factors. Multipliers may be applied to individual fault connections or, if the named fault (FNAME) option has been used, a single factor may be applied to the entire fault, using the Named Faults (MULTIR) data input option.
In this exercise, we want to partially seal the faults around wells W1 and W2. Additionally, we will be applying different sealing factors to sections of each fault.
Note
Fault multipliers are cumulative and are processed the order in which they are entered.
1. Use the Nexus View software to help you determine which faults may be sealing and their location (that is, the range of gridblocks to which the faults are adjacent).
2. Create a new case named history3 under the history study. Remember to highlight the history study first, then create a new case.
3. Open history2.vds in the SimDataStudio software and save it as history3.vds.
4. In the CORE data tab, expand the Grid related data branch and select Multipliers - overrides > Connections transmissibility modifications.
Notice the transmissibility modifications are in an Include file.
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You can click to insert a new row and modify the transmissibility multipliers as shown below:
Alternatively, you can open this halcon30x20.fml Include file to edit it directly. In this exercise, you can include a pre-prepared file named “halcon1_fault.inc.”
5. Highlight the halcon30x20.fml file by clicking it.
6. Click to bring up the Include File Selection dialog box and select the halcon1_fault.inc file.
7. Click Open. This will replace the original fault multiplier file with the modified file. Use the View Include File button to look at the multipliers in this file.
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8. Select Simulation Data > Generate Simulator Data File > Nexus files from the menubar to generate history3.fcs.
9. Create a new Nexus simulation job:
•Make sure history3.fcs is the FCS File.
• Run the simulation and see if you can improve the history match.
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Adjust Contacts
Now you may have a better pressure match, but you still may not have an adequate match for water production on some of the wells. To improve this match, experiment with adjusting the water-oil contact upward (be careful with this option, because moving WOC will change OIP).
1. Create a new case named history4 under the history study.
2. Open history3.vds in the SimDataStudio software and save it as history4.vds.
3. In the CORE tab, click Equilibrium Data.
4. Change WOC from 9385 to 9380.
5. Select Simulation Data > Generate Simulator Data File > Nexus files from the menubar to generate history4.fcs.
6. Create a new Nexus simulation job.
7. Make sure history4.fcs is the FCS File.
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8. Run the simulation and see if you can improve the history match.
Hint
Check the QWP and WCUT of wells W6, W7, and W8.
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Adjust Permeability
Now you should have water production but no good match for some wells. You may consider modifying the permeability around those wells. In this exercise, you want to reduce the water production from well W8.
1. Create a new case named history5 under the history study.
2. Open history4.vds in the SimDataStudio software and save it as history5.vds.
3. On the EXEC tab, double-click Well Perforations, and notice that well W8 is perforated at i=9, j=,5 and k=1.
4. On the CORE tab, expand Grid related data > Grid arrays, and double-click Physical Property Arrays.
5. Set KX as the Property.
6. Click the New Row icon ( ) to add a new row and multiply the values of KX in i=8-10, j=4-6, k=1 by 2.2.
7. Make the same change to KY.
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8. Select Simulation Data > Generate Simulator Data File > Nexus files from the menubar to generate history5.fcs.
9. Create a new Nexus simulation job.
10. Make sure history5.fcs is the FCS File.
11. Run the simulation and see if you can improve the history match.
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Discussion Points
You should now be able to discuss the following:
• What are three important history-matching strategies?
• How do you modify, override, and adjust array data to match historical performance more closely?
• What tools are available to help you take into account the effect of aquifers on reservoir behavior?
• How do you modify transmissibility factors for standard and non-standard fault connections?
• How would you improve model accuracy by adjusting the water-oil contact?
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You have just finished working with a history-matching problem in the previous chapter. This chapter will help you continue the same study into the future.
You will create a realistic reservoir management model by defining a simple surface network. You will install the pipes that connect the ten wellheads to the three collection points, and link these collection points to the outlet.
Instead of honoring well rates as you did in the previous chapter, you will be given network pressure constraints to apply to the model. The Nexus® software will determine the rates and allow you to explore what-if scenarios. This chapter also introduces the concept of hydraulics method, and will show you how to run a simulation using a RESTART record other than time zero.
Introduction
This chapter begins with a discussion of some of the technical aspects of Nexus modeling as it relates to pressure control and restarts. Then, it provides an exercise that will help you learn how to use these concepts in a practical way. By the end of this chapter, you should understand how to:
• Create a simple surface pipeline network (SPN) using the SimDataStudio™ (SDS) software.
• Operate the Nexus software in simple predictive mode (network pressure constrained).
• Restart a simulation run at a non-zero time.
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Surface Network
The Nexus software models the well and surface facility system as:
• A set of nodes
• Connections between the nodes
• Connections from nodes to reservoir grid cells (perforations)
• Connections from nodes to sinks (production)
• Connections from sources to nodes (injection)
The Nexus software automatically generates a gridded wellbore representation for each well from the well perforation data (WELLSPEC) and from the well connection data (WELLS). In the case of individually constrained wells with no modeled network, all required network data including pressure and rate constraints may be simply input using the well name, as in conventional simulators.
Wellbore Subnetwork Configuration
Each entry in the WELLSPEC table represents a perforation, a connection from the specified reservoir grid cell to a network node at the center of the wellbore section, or an unperforated node in the wellbore connected to one or more perforated nodes.
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A single network node, called “perfnode,” is created for each flow section at the depth specified in the WELLSPEC table for the first perforation in the section. All perforations in the section are attached to its perfnode, and these perfnodes are automatically connected to one another sequentially in the order of their section number.
The well connection data (WELLS) define the properties for the well’s bottomhole node connection to the rest of the network. By default, the rest of the network consists of a SINK for production wells and a SOURCE for injection wells. The length of the bottomhole connection is the distance from the bottomhole node to the connecting perforation. Alternately, user-defined nodes can be added in the surface network model with the NODES keyword and their connections defined with the NODECON table.
Instead of the NODECON table, the data could also be input using a WELLHEAD table, which is intended to provide simplified input for the special connection from the bottomhole to surface, and is particularly useful when there are no other connections in the network.
The WELLHEAD table creates a new node at the wellhead, creates a new connection from the wellhead node to a source or a sink, and redefines the well connection (which was created in the WELLS table) to connect the well bottomhole node to the wellhead node (that is, the well connection becomes the tubing from the bottomhole to the surface).
The primary variables in the network model are node pressures and component mass rates in perforations and network connections.
The network model equations consist of:
• modified well model equations describing the component or total flow between the reservoir and the network nodes in the wellbore through the perforations
• component mass balances at nodes
• a combination of hydraulic relationships (hydrostatic gradients, tables, or correlations) relating the node pressures of each connection, rate constraint equations for connections, pressure constraint equations for nodes, equal composition constraints for multiple connections outflowing from the same node, separation equations, or source composition constraints
All the data for a surface network is entered via the surface.dat file included in the RECURRENT_FILES section.
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Node Definition Data (NODES)
User-defined nodes in the surface network model are defined as follows. (For more detail on this keyword, refer to “Node Definition Data” in the “Surface Network” section of the Keyword Reference document.)
In the SimDataStudio software, you can define the network nodes as shown below.
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Node Connection Data (NODECON)
Node connection data define networks or modify the default well subnetwork configurations. (For more detail on this keyword, refer to “Node Connection Data” in the “Surface Network” section of the Keyword Reference document.)
NODECON
NAME NODEIN NODEOUT (IPVT) (IWAT) (IBAT) (TYPE) (METHOD) (LENGTH)
conname nodein nodeout (ipvt) (iwat) (ibat) PIPE or GRADCALC (length)
......
......
ENDNODECON
In the SimDataStudio software, you can define the network connections as shown.
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Network Pressure Constraints (CONSTRAINTS)
Pressure constraints may be input for nodes or wells. PMIN constraints are allowed in production subnetworks only, and PMAX constraints are allowed only in injection subnetworks. A PMIN constraint is required for the terminal node in a production network, and a PMAX constraint is required for the terminal node in an injection network. Pressure constraints are input in a CONSTRAINTS table, which may also contain input for rate constraints, minimum rate limits, and well limits.
By default, the first occurrence of a node in a time period (that is, between TIME inputs), will clear all previous constraints for that node. All subsequent occurrences of the same node will add to the previously specified set of constraints.
Constraint data is specified as follows:
CONSTRAINTS
name PMIN pmin
PMAX pmax
PWMAX pwmax
PGMAX pgmax
BHP bhp
THP thp
DPBHMX dpbhmx
CLEAR
CLEARP
ENDCONSTRAINTS
(For more details on Network Pressure Constraints, refer to “Network Pressure Constraints” in the “Surface Network” section of the Keyword Reference document.)
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Define Hydraulics Method
You can use hydraulics methods to relate tubinghead pressure to bottomhole pressure and three-phase flow rates. Each method can be defined independently, and more than one well can refer to the same method. The rate can be defined as either the oil rate, liquid rate, or gas rate, and the other two cut parameters will be expected accordingly.
All the data for a hydraulics method is input in a single file. Using different variables, you can define hydraulics tables as listed below:
• Hydraulics Data Using Oil Rates with Gas-Oil Ratios
• Hydraulics Data Using Oil Rates with Gas-Liquid Ratios
• Hydraulics Data Using Liquid Rates with Gas-Liquid Ratios
• Hydraulics Data Using Liquid Rates with Gas-Oil Ratios
• Hydraulics Data Using Gas Rates
• Hydraulics Data Using Water Rates
• Hydraulics Data Using Wet Gas Rates and Mean Molecular Weight
• Hydraulics Table Extrapolation Limits
• Water Injection Hydraulics Correlation Data
A hydraulics table contains several lines of variable data followed by columnar data, as shown in the following example:
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Hydraulics files are included in a case in the NET_METHOD_FILES section as follows:
NET_METHOD_FILES HYD method 1 filename1 HYD method 2 filename2
(For more detail on hydraulics method, go to Help > Simulators > Nexus Keyword Document and refer to “Hydraulics Data” in the Keyword Reference manual.)
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Restarting Runs
Restarting a run saves some of the work involved in processing a model by allowing you to start the run over at a specific point in time. To set a restart run, you will need to either set Restart Options from Output Options in the SimDataStudio software, or manually insert a RESTART card after the data you want to restart in the casename_runcontrol.dat file.
TIME MM/DD/YYYY OUTPUT RESTART TNEXT ENDOUTPUT
To specify a restart run, a RESTART card is required in the .fcs file to restart a simulation run at a non-zero time. This is followed by the TIME or TIMESTEP keywords, and the restart directory name.
The keyword TIME may be followed by a time in days (or hours for LAB units), a date, or the keyword LAST to indicate a restart from the last restart record written. The keyword TIMESTEP is followed by an integer specifying the timestep for the restart. The restart directory name is the name of the restart directory created by the initial run, which is named “casename.rst,” where “casename” is the case name specified for the initial run. If the .rst extension is not present, the program will first check for the existence of the restart data using the restart directory name as input. If it does not find restart data, it will add the .rst extension and check again. The RESTART keyword is only present if the run is a restart. (Default: Not a restart run)
For example, the following two lines function identically to specify a restart run starting from timestep number 11, whose corresponding day is 21 days from the beginning of the simulation:
RESTART TIMESTEP 11 casename.rst RESTART TIME 21. casename.rst
You can also use the LAST keyword to specify that restart begins at the last record found in the restart file.
RESTART LAST casename.rst
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Exercise: Running in Predictive Mode
This exercise shows how to define a basic surface pipeline network and use some of the concepts learned on the preceding pages of this chapter to set the network pressure constraint. Although instructions are given to use the SimDataStudio (SDS) software, everything here can be done by manually editing the input data files.
In this exercise, you are given the last history-matching model from the previous chapter. A schematic diagram of the reservoir with network nodes is shown below.
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1. Open the history study in C:\Nexus_basic_data\WS7.
The history5 case is shown under the history study.
2. Create a predictive case named pred as a child case of history5:
• Highlight the case history5 and click the icon to create a new case named pred.
• Open history5.vds in the SimDataStudio software from the \WS7 directory and save it as pred.vds.
3. Define the utility data.
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• Go to the EXEC tab, double-click Utility Data, define an End Date, and extend for two years.
• Check the Restart Run checkbox.
A text box will appear.
•Click after “in restart file:” and, when the Select directory for Nexus restart window appears, choose history5.rst in the WS7 data directory and click Open.
A new text box appears.
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•Click to specify the date. Select last restart date.
Now, your Restart Runs section should look like this:
Note
If the restart file does not show immediately, click to insert it again.
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4. Generate new output requests for the prediction run by double- clicking Output Options. Right-click the restart date to generate new dates at one-month intervals.
5. Import the hydraulic tables bhptab_1.txt, bhptab_2.txt, bhptab_3.txt, and bhptab_4.txt. These tables will be used for wellbore hydraulics calculations.
• Double-click Hydraulics Tables.
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• Click on "Table Management" icon ( ) to import the hydraulic table.
• Open bhptab_1.txt in the \WS7\hydraulics_table directory.
The Table Import Selection window appears.
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•Click OK to import the file.
•Click Table management and select Add new hydraulic table.
• Follow the same steps to import bhptab_2.txt, bhptab_3.txt, and bhptab_4.txt.
6. Define the network profile. Four network nodes will be placed in the reservoir – three corresponding to gathering centers (GC1, GC2, and GC3) and the other to the outlet node (OUT1).
• Double-click Surface network nodes.
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• Click the date when the changes start.
Note
Selecting the correct date is very important. Defining the network at a date earlier than the restart date will cause the network data to be ignored.
•Click Add network and select Production network.
• When prompted, change the default node name to OUT1.
• Right-click OUT1 and select "Add new child interconnection node".
• When prompted, change the default node name to GC1.
• Right-click GC1 and select Connect wells to network > Group of production wells.
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• Check W1, W2, W8 and D1, then click Finish.
• Follow the same procedure to add GC2 and GC3, and to assign the wells to those gathering centers. Note that W3 is directly under OUT1.
7. Define the network pressure constraints:
• Define a minimum pressure constraint of 100 psia for the OUT1 node.
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• Define a minimum pressure constraint of 150 psia for the WH_W8 node.
• Define a minimum pressure constraint of 500 psia for other wellhead nodes.
8. Define the surface network connections:
• Double-click Surface network connections.
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• No data will be shown until you click the date card for Dec 1st 2001.
• In the TYPE column, change all Gradient to PIPE.
• In the METHOD column, select the BEGGS pressure drop correlation for each pipe.
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• Assign hydraulic methods by clicking the cell in the METHOD column and selecting the appropriate method. Choose the hydraulics method numbers from the table below
Pipe lengths for the connections between the gathering center nodes and the OUT1 outlet node are given in the following table:
Node In Node Out Length (ft)
GC1 OUT1 4205
GC2 OUT1 2851
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Node In Node Out Length (ft)
GC3 OUT1 3783
Wells are assigned to the nodes according to the table above, with length of the pipe connecting each wellhead to the network node and the depth to the top perforation.
• Assume that the tubing from the top perforation of each well to the wellhead is vertical, and that each wellhead is at elevation 0.0 ft. Also, each of the wellhead node connections is a pipe at constant elevation of 0.0 ft.
• Define input diameters for each connection with BEGGS correlations. Set the diameter for connections from wellhead to GC as 4 inches, and the diameter for connections from GC to OUT as 8 inches.
• Define a roughness for each pipe of 0.0005 using the ROUGHNESS parameter.
Now, your table should look like this:
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Note
Entering LENGTH and DDDEPTH for the connections from the bottom hole to the wellhead nodes is not required if the wellhead is at a depth of zero. For wells where wellhead depth is not zero, the information should be entered so Nexus can make the correct adjustments to the hydraulic table calculations.
9. Select Simulation Data > Generate Simulator Data File > Nexus files from the menubar to generate the Nexus model.
A warning pop-up message will appear setting the Temperature in 100 F for the surface connections. Accept the message and generate the data.
10. In the Nexus and VIP Simulation window, make sure pred is highlighted.
11. Check “Generate SPN” box to be able to view the network in SurfNett Software. Click "Yes" to accept the overwrite of existing SPN data (currently empty).
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Make sure pred.fcs is the FCS File.
..
12. Submit the Nexus simulation job for pred case.
13. Bring up the SimResults™ software to see the how the trends are extended into the predictive phase. When you are finished, you have successfully made a predictive run.
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Discussion Points
You should now be able to answer the following questions:
• What constraints could be used in a model to run a predictive case?
• Which kind of file does the Nexus software use to store the surface network data?
• How do you set a restart run?
• What is a node? What is a node connection?
• What data input do you need to define a basic surface network?
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7-26 Nexus® Software R5000.4.8 Basic Reservoir Simulation Chapter 8 Introduction to SurfNet Software
Viewing Results in SurfNet Software
One of the primary capabilities of Nexus is to model both the surface and subsurface and solve them simultaneously. Therefore, it becomes very important for the user to be able to build and QC a surface network easily prior to simulation, and examine the results of the surface network after simulation. SurfNet is both a pre-processor for generating and QC’ing surface network data and a post-processor for analyzing simulation results. SurfNet has the capability to display multi-reservoir surface networks as well as individual surface network data, it has plotting and charting capability and it can import GAP models directly into the VDB for use by SimDataStudio. Note that importing GAP data requires a PETEX OpenServer license.
In future SurfNet will be able to give pre-process capability, enabling user to graphically create a surface network.
Tips on Launching SurfNet
SurfNet cannot be opened using an empty active case. For best results the following steps are suggested.
Import Nexus or GAP Network Model • Make sure no CASE is currently active in the Nexus desktop • Launch SurfNet • Select the option to import Nexus or GAP Network model • Select the desired Nexus case file (.fcs) or GAP file (NOTE: The Nexus case must contain NODE/NODECON data in the surface data file) • If no VDB exists with the corresponding Nexus or GAP name then one will be created • WARNING: If a VDB study/case exists with this name and the case contains SPN class data, importing Nexus or GAP data will overwrite the existing SPN data
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Open existing study/case containing SPN class data • Make the desired CASE active • Launch SurfNet
Open existing study/case not containing SPN class data • Follow the process noted above for importing Nexus or GAP network models
Open SurfNet as a pre-processor (EDIT mode) • WARNING: To open in EDIT mode SurfNet requires a VDB STUDY/CASE with GEO, CALC or INIT class data. • Make sure no CASE is currently active in the Nexus desktop • Launch SurfNet • Select the option to Open Study/Case • Check the box ‘Open in edit mode’ • Navigate to the directory containing the desired VDB and specify the study/case to be used.
Load a previously saved SurfNet session • Make sure no CASE is currently active in the Nexus desktop • Launch SurfNet and load the saved session
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Viewing Results in SurfNet Software: Loading Data from a Case
In this workshop, we will open a study/case with existing SPN class data and work with some basic features of SurfNet. We will also work through the process of importing network data from an existing set of Nexus input data..
1. From the Nexus Desktop, highlight "Default Session" and Launch SurfNet by clicking on
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The SurfNet "Start Page" appears.
.
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2. Under "Open/Import", to load the case data, click "Open study/ Case…" or click the icon.
3. Load the data by navigating to folder WS8 and the study (.vdb) and case.
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.
Note:
Since this case already has SPN class data we could also have done this making the cass active in the Nexus desktop and directly launching Surfnet.
The Network data is loaded and shown under the "Main Canvas" tab:
You can load other cases directly from this window by clicking on load icons or from the "File" menu.
4. Re-scale and zoom as needed using the mouse or by adjusting from icons and display the network at time Step 952 days from "Time Step (Days) icon
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. You can use the drop down icon to switch between the time steps and date:
As you march through "Time Step", the time steps with "* " indicate that the network configuration has changed at that time. Typically this will correpdond to sections of the network being activated or deactivated, as occurs when wells are shut-in or new wells are brought online.
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The network can be active or inactive at any time step (not connected). The inactive network (branch) is colored grayed and is distinctive from the rest of the network:
5. You can expand or shrink the network at any branch by double clicking on the node above that branch. The nodes are shown by either circle (general node) or triangles ( which is wellhead_node, and which is the well node). Double click on "Node_67" node which is before the terminal node SINK at the most downstream of the network. A "+" appears, indicating the hidden network branch underneath. There is a special internal node for perforations . In Nexus, the user can define, general nodes , well nodes , and well_head nodes , The perforation nodes are defined by default internally.
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.
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Expand Node_67 node and try expanding the well nodes to see perforations. The % # sign indicates the perforation(%) number(#).
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6. Select "Node_67 " connection, by clicking on it (the connection between Node_67 and the SINK). Note: A connection is between 2 Nodes and generally represents a (section of) pipe, or tubing.
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7. Plot cumulative oil rate for "Node_67" connection by:
• Click on "Charting" icon. • Select the "Cumulative Oil" from the property section • Click on "Plot vs. Time" icon
You can minimize the chart if needed to.
8. Select "Node_67" node, and click on Display constraints icon
9. Display PMIN by clicking on "ADD" icon
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10. Display Oil,Gas, and Water rates for "Node_35_sep_1" connection. Plot those values vs. time using different formats in the "charting section".
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11. Take a snapshot by clicking on
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12. Select "Snapshot tool" icon, highlight the snapshot image and save it as pdf.
13. Save the layout and by clicking on so it can be used for future references.
One benefit of SurfNet is to be able to directly load the surface network for verification of the connections. Often times, the user has to manually create a surface network using text editor to connect nodes and assign connections to valves/separators/ pumps etc. Therefore, there is a need to verify the network visually before even running the simulation. In SurfNet the user can load the Surface network using the case file (.fcs) in which it points to the surface.dat file. To load the surface network from the case file:
14. Click the Import Nexus Network Model … icon.
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Load the Nexus case file base1.fcs (if there is no vdb SurfNet will create one, assign a case and create SPN folder inside that case for future visualization). Click Close to accept the defaults.
15. Click Import.
Since the new vdb is empty (no results of the simulation is saved under RECUR folder of spe_show case folder), all time steps are marked with "*" and represent times at which the network configuration has changed. However, the user can examine the surface network image and verify the overall layout of the network.
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8-18 Nexus® Software R5000.4.8 Basic Reservoir Simulation Chapter 9 Connecting a Group of Reservoirs into a Single Network
This chapter presents a more complex problem, in which you have separate standalone simulation models in the Nexus® software format for each reservoir and where each reservoir has its own surface pipeline network with surface facilities. The Nexus software allows you to connect the group of models through a surface pipeline network and then run them as a single model with common constraints on the surfaces.
Introduction
In this chapter, you will create a merged surface pipeline network (SPN), combine multiple Nexus models into a single multireservoir model, and connect them with merged surface pipeline network. You will start with merging individual surface networks from different reservoirs and then combine them to create the multireservoir model. Proceed to the next page to begin the set of workflows.
In this chapter, you will:
• Create a new study and case. • Merge multiple reservoirs. • Create a merged surface pipeline network (SPN). • Join multiple models to create a single multireservoir model. • View the multireservoir model data in the SimDataStudio™ (SDS) software. • View the multireservoir model in the Nexus View® software. • Submit the job. • View the post-simulation results.
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Exercise: Create a Multi-Reservoir Study and Case
In this exercise, we connect a group of individual reservoirs (Res_1, Res_2, Res_3) to a common surface network. Consider the following diagram. Each individual reservoir has a surface network terminated at Sat1, Sat2, and Sat3 nodes. Using SDS we connect these terminal nodes to Surface nodes, Node1 and Node2.
Step1: View individual reservoirs and their surface network in Nexus View
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1. Click on "Default Sessions" on Nexus Desktop and launch Nexus view by clicking on icon ( ).
2. Click on File > Load 3D Grid and navigate to WS9/res1 folder and select res_1.vdb.
3. Select "Surface Network" on the "data Selector" tab and check
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"Display Network".
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4. Click on File > Load 3D Grid and navigate to WS9/res2 folder and select res_2.vdb.
5. Select "Surface Network" on the "data Selector" tab and check "Display Network".
6. Repeat step 4 and 5 to load res_3 and display its surface network.
7. From the "project" dropdown menubar, select each individual reservoir model and click on "Apply". You should be able to see reservoirs on one screen altogether:
In the next step we will connect these individual reservoirs using SDS to a common Network (Node1 and Node2).
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Join Multiple Models to Create a Single Multireservoir Model
You will now use the SimDataStudio software to combine the Nexus models into a single multireservoir model.
1. Create a new study and case in WS9\Output folder and name them multires1.
2. Make sure multires1 case is the working case by highlighting it.
3. Click the SimDataStudio icon ( ) to launch the SimDataStudio software.
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4. When the New SimDataStudio Case dialog box displays, click "Use assistant to create a Nexus multireservoir case".
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The Multireservoir builder wizard displays.
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Connect the Networks in Multireservoir Builder Wizard
1. Click the New icon ( ).
The Multiple Case File Selection dialog box displays.
2. Click the Browse icon ( ) after the Show files below field and navigate to C:\Basic_Nexus\WS9\.
3. If the Select root directory dialog box displays, select the WS9 folder and click OK.
The Multiple Case File Selection dialog box displays all models available in the WS9 folder.
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4. Check all three available cases and click OK.
The Multireservoir builder wizard displays the three reservoirs in the multireservoir dataset.
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.
Note
You can specify the Reservoir_name, Map_file (i.map) file and Map_data_origin as needed. If there is no individual map file, you will not be able to visualize the multireservoir model.
5. Click Next.
The Multireservoir network interconnection panel displays.
6. Click and Select "Production Network”.
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By default Node1 is created. Accept the default name and right click on it as select "Add new child interconnection node". Accept the default name (Node2).
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7. Click in the "Nodes pressure limit - bar" cell for Node1 and assign pressure limit of 25.
8. Right-click NODE1 and select Node Properties. Set X = “404,000.00 meters”, Y = “93,500” meters, and Z = “0.00” meters.
9. Repeat setp 8 for NODE2, with same X and Y values, but set Z = “200.00” meters.
10. Click “Next”.
The Connect individual reservoirs to interconnect network dialog box displays.
11. Connect all reservoirs to Node2 by clicking the drop-down arrow and selecting Node2.
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12. Click Next to open the Define interconnections properties and constraints panel.
This panel displays the properties and constraints for your interconnect network connections. Just as in the single reservoir, nodes are connected to gathering centers.
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13. Specify the Type and Method for each connection by clicking the drop-down arrow and selecting PIPE and GRADCALC, respectively.
14. Click Next to open the Nexus Data Set Generation… panel.
15. If you get a message indicating that some connections do not have an IPVT method specified, click OK.
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This, by default, will use PVT method one. However, you can specify which PVT method to use by entering info in IPVT field.
Users will get a warning message that the imap control parameters are only generated for multifield models using structured grid input format for all reservoirs.
16. Check the Status column for errors. This model has no errors indicated.
17. Click Finish to generate the multireservoir model. Progress indicators appear while the model is being generated. The SimDataStudio window displays the generated data.
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View the Multireservoir Model Data in SimDataStudio™ Software
The Multireservoir pane at the bottom of the right panel lists the three reservoirs. Data files are listed in the multires1.fcs tab at the bottom of the screen.
1. Expand the bottom panel by dragging the horizontal bar upward.
2. Review the list of data files.
SimDataStudio generated a .fcs file for a multireservoir model.
The multireservoir file contains three different .fcs files, each being a standalone Nexus model.
The multireservoir model includes common OPTIONS, RUNCONTROL, and SURFACE files.
3. Double-click the Network connections label on the tree.
The Surface network connections screen displays the network connections properties and constraints.
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4. Click the Save icon ( ) to save your multireservoir model in SimDataStudio format.
5. Close SimDataStudio by selecting File > Exit from the SimDataStudio menubar.
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Exercise: Submit the Job
1. In the Nexus Desktop window, click to create a new Nexus simulation job.
2. Check "Generate SPN" box, and click ok to accept the warning.
3. Click Start to submit the job.
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View the Post-simulation Results
1. In the Nexus Desktop window, make sure multires1 is the working case by highlighting it and launch Nexus View. When prompted to "Chose Available Reservoirs" window, under "well availability" select "all wells"
2. Select "surface Network" from "data selector" tab and check "Display Network" to view multireservoir network. You need to zoom in, to be able see the node names.
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3. Similarly highlight multireservoir case on Nexus desktop window and lunch "SurfNet" and examine the multireservoir network.
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Discussion Points
You should now be able to answer the following questions:
• When merging multiple reservoirs, what will you need to add?
• Where should you save the well planning file? Why?
• What tool assists with the merging of multiple reservoirs?
• What tool can you use to view the multireservoir model?
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9-24 Nexus® Software R5000.4.8 Basic Reservoir Simulation Chapter 10 SimConvert™ Software
The Nexus® software includes other options that help you manage the data within your specific environment. The SimConvert™ software makes it easy for you to export case studies to other formats and import data from map/plot files, RESCUE, and ECLIPSE™.
Introduction
This chapter explains some of the SimConvert options that are available. By the end of this chapter you should be able to:
• Work with the standard SimConvert user interface.
• Import or export map data into/from the Nexus software.
• Import or export production data into/from the Nexus software.
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Understanding SimConvert™ Software
Throughout the simulation workflow, there are times when it is useful to:
• Export map or plot information from the VDB database for use in other applications.
• Import map or plot data from other applications (such as ECLIPSE) into the VDB.
• Create data outside the VDB and selectively import the files that you want.
The SimConvert software is a utility that is designed to help you quickly convert data between the formats you need. The following exercises show how to start the SimConvert software, open a study and case, and use the various import and export options.
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Exercise: Open a Study/Case in SimConvert™ Software
The following steps show you how to open the SimConvert software:
1. Select an existing case (the multires1 case from the last workshop is shown in the example below).
2. Click the icon to launch the SimConvert software.
The SimConvert main window opens.
3. Click the icon located next to the Study name field.
The File Selection dialog box opens.
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4. Navigate to the WS10 folder.
5. Select the halcon.vdb file and click Open to open it.
The name displays in the Study name field.
Notice that the case associated with the study also displays in the Case name field. If the study contained multiple cases, you would be able to select them using one of the following methods:
• Click the pull-down menu located next to Case name and select the case from the menu.
• Click the desired case name in the list below the Case name field.
• Click inside the Case name field and type the desired case name.
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Exercise: Using the SimConvert™ Software Interface
The various options in the SimConvert software are shown along the left side of the main window. The (-) and (+) icons let you open or close various branches in this tree diagram.
• Click the icon to close a branch of the Options list.
• Click the icon to open the branch you just closed.
• Click any option (below the main branch) to select it. For instance, click Spreadsheet below Export Map Data. This lets you export map data to a spreadsheet.
Notice that each option you select changes the layout in the main panel of the SimConvert window.
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The SimConvert View tab can help you decide what data you want to export.
In this example, you are looking at layer 1 porosity of the initialized grid.
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Understanding the Map Data Export Options
You can export map data from the .vdb file:
• As a text spreadsheet for analysis
• In GRIDGENR™ software or Z-MAP format for mapping or regridding within these applications
• As a text file that can be imported back to the VDB as a binary file using the VIP Convert Import Map/Plot option (for example, to add a case to a new VDB)
• As well, perforation, fault, cornerpoint, property, and grid dimension files that can be read as .wij, .fpf, .fml, .cor, and .lgr files (for example, for use in VIP Data Studio)
• In RESCUE format (property and geocellular grid data)
• In ECLIPSE format (property and geocellular grid data)
Click each option under Export Map Data on the left side of the SimConvert main window and notice how the main panel changes. The following pages provide specific exercises showing how to use the Export to Spreadsheet option.
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Exercise: Export Map Data to Spreadsheet Format
Use the following steps to export map data to a spreadsheet format.
1. Select the Spreadsheet option under Export Map Data on the left side of the SimConvert main window.
2. Click the Export button ( ) located on the SimConvert toolbar.
The Dump Map Spreadsheet Data panel opens.
Class types with available data
Grid list
Select Check All or Clear All items in Grid List
Export file path and name
The table in the center of the panel summarizes data being exported:
Column Purpose
Sel Lets you select which grids to export (if more than one is listed). All available grids are selected by default.
Grid Shows the grid name for each grid in the data file.
I-J-K Shows the gridblock range for the grid on this row (number of gridblocks in the I, J, and K direction).
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Column Purpose
Timesteps / Timesteps and properties for recurrent data only. (Timesteps do Properties not exist for other classes of data.)
Notice that the Class types with data available for export are active (not dimmed) in the upper left corner, while those without available data are inactive (dimmed). In the previous illustration, recurrent data (RECUR) is selected. Make sure it remains selected during the following steps.
3. Double-click the row below the Timesteps and Properties columns to filter data for the associated grid.
A selection list opens to display the available data, as shown below.
Timestep Filter List Properties Filter List
4. In the Timesteps selection list, scroll down the list and click timestep 1705 to select it.
5. In the Properties selection list, click ALL to export all properties.
6. In both lists, check the Apply to all grids checkbox. Otherwise, the selections will be applied only to the current grid if multiple grids exist (i.e., local grid refinement, multiple reservoirs, and so forth).
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7. Click Export.
Notes
• The default path for the spreadsheet is your current directory. • The default file name is
8. When the export is finished, click Close to close the Dump Map Spreadsheet Data panel.
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Exercise: Viewing the Exported Data
If the exported file is in text format, you will have the option to view the data.
1. Once the export process is complete, select File > View Files ... from the menubar and select your previously specified output.
2. The file opens in your system’s default text editor. WordPad is shown in the example.
3. Close the text editor by selecting File > Exit.
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Understanding the Production Data Export Options
You can export production data from the .vdb file:
• As a text spreadsheet (raw simulated production data)
• In generic Landmark® AFS format for use with economic and surveillance applications (simulated monthly/annual averages)
• As a text file that can be imported back to the VDB as a binary file using the SimConvert Import Map/Plot option
• As a text file that can be used for analysis or as an Include file for history matching in another simulation run
Click each option under Export Production Data on the left side of the SimConvert main window and notice how the main panel changes. The following pages provide specific exercises showing how to use the Export to Generic Spreadsheet option.
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Exercise: Export to Generic Spreadsheet
The Generic Spreadsheet option is used to export raw production data to a spreadsheet format. Use the following steps:
1. Select the Generic Spreadsheet option under the Export Production Data branch of the SimConvert options tree.
2. Click the Export button ( ).
The Dump Production Generic Spreadsheet File panel opens.
3. Click in the first column on the list, as shown below, to deactivate (uncheck) the NODE, CONN, REGION, CONNLIST, and TARGET classes. You will export only WELL and FIELD data.
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4. Double-click in the first row in the Properties column to filter data for the associated class (well).
This displays a list that you can use to display the available properties as shown below.
• Click OOP, then control-MB1 (hold the Ctrl key and click) QOP, QGP, QWP, and BHP to select them as the properties to export. Click OK to close the Properties dialog box.
5. Click Export.
6. When the export is finished, click Close.
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7. Select File > View Files... from the menubar to open your exported generic spreadsheet in your system’s default text editor.
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Understanding the Import Options
The Import options let you specify a file to import into a VDB database. You can import map and plot data that was created outside the VDB, or you can import data from ECLIPSE, RESCUE, and GAP models.
• VIP® program plot and map files
• Files generated by the ECLIPSE application
• Property and geocellular grid (flavor B, multiple units with single block or global grid) data from RESCUE format
• Import a model from GAP format as a VDB file (this option requires that a PETEX OpenServer license be available).
Click each option under Import to VDB on the left side of the SimConvert main window and notice how the main panel changes. The following pages provide specific exercises showing how to use the Import VIP MAP/PLOT Data option.
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Exercise: Importing Map/Plot Data
Perform the following steps to import separate map files and observed data.
1. Select the VIP/Nexus Map/Plot/OBS option under Import to VDB on the left side of the SimConvert window.
The main panel changes to match your selection.
2. Under the "Case Options" section, click the Folder icon ( ) located next to the "Study name" box.
The Open dialog box opens.
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3. Type new in the File name field and click Open.
4. Enter new in the Case name field.
5. In the Input Files section, click the icon located next to the Map file (Init).
The Open dialog box opens.
6. Select novdbi_lgr.map and click Open.
7. Repeat this process to import the recurrent map file novdbr_lgr.map.
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8. Click the Import button located near the top of the SimConvert main panel.
9. Once the conversion process is finished, you can open the new .vdb study and new case from the Nexus Desktop® software window, and display it in the Nexus View® software.
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Exercise: Importing Rescue File
If you have Petrel data, one method to import the information into VDB is to export Petrel into rescue format. Simconvert allows you to import the rescue format files into vdb.
Perform the following steps to import separate map files or plot data:
1. Select the Rescue Model option under Import to VDB on the left side of the SimConvert window.
The main panel changes to match your selection.
2. In the Case Options section, click the Folder icon located next to the Study name field.
The Open dialog box opens.
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3. Type run in the File name field and click Open.
4. Enter run in the Case name field.
5. In the Input Files section, click the icon located next to the Rescue file.
The Open dialog box opens.
6. Select halcon_halcon_INIT.rescue.bin and click Open.
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7. Click the Import button located near the top of the SimConvert main panel.
The Import RESCUE Data dialog box opens.
• Select the property group. If the RESCUE data has property groups, click the drop-down box beside the Model property group field and select the property group to import from the menu.
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• Map the properties. In the GRIDGENR Property Mapping tab, click the drop-down arrow beside each property and select the corresponding RESCUE property to map.
• Select user-defined properties (optional). In the User-defined Property tab will show all properties in the Rescue file. By default, all properties not assigned in the GRIDGENR Property Mapping tab will be checked. Click Clear all to clear the checked boxes and then click the checkbox beside each property you want to import. Your selections will be imported as user- defined properties, using the same name as is shown in this list. Select three or four properties at random from the list below..
• Import the properties. When all the selections have been made, click the Import button located at the bottom of either panel. The properties import into the specified VDB.
8. Once the conversion process is finished, you can open the run.vdb study and new case from the Nexus Desktop window.
9. Select File > Exit to close the SimConvert window.
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Discussion Points
You should now be able to answer the following questions:
• Which kind of data file can the SimConvert software import?
• Which kind of data file can the SimConvert software export?
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This chapter introduces the PowerGrid™ software to prepare a grid for use in the Nexus® software simulation application.
Introduction
The PowerGrid software provides the following functionality:
• advanced gridding capabilities to manage properties, regions, and reservoir units, visualize property histograms, apply fault transmissibility multipliers, create local grid refinements, and extract/convert a portion of the grid
• reservoir modeling capabilities to upscale geological models into simulation scale models using a variety of static- and fluid- based methods, such as harmonic series, parallel tubes, and direct pressure solution
The PowerGrid software’s novel approach maintains the geological resolution near faults to prevent wells from switching from one side of a fault to another in areas where fault location is a key constraint. It also provides an automatic upscaling option which computes the optimum coarsening for a user-defined number of layers using any one of several property values.
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Exercise: Launch PowerGrid™ Software
1. From the Nexus Desktop window, click on “Default Session:, change the “Measurement Units to be used for Nexus View” to Metric Units, then select File > Open/Create Study and open the wfarm study from the WS11 folder.
2. Highlight the wfarm case and click to launch the Nexus View software.
3. In the Nexus View window, select Launch > PowerGrid.
Eight new icons appear in the tool bar.
Icon Name Description
Property Manager Add or manipulate properties.
Histogram Visualize grid properties, including computed quality measures.
Fault Assign fault transmissibility multipliers Transmissibility to faults. Multiplier
Reservoir Unit Create reservoir units for use in Automatic Manager Layer Lumping in the Upscaler.
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Icon Name Description
Region Manager Add regions and modify region properties. You can define regions around wells and/or faults, with favorable property characteristics that should retain a finer scale in the simulation scale grid, in a window or polygon, from a dynamic region, or using a script.
Refinement Perform local grid refinement to refine the Manager grid further within any volume of interest.
Extraction Extract a portion of the grid into a new grid to focus in on one reservoir area.
Upscaler Upscale the grid. Workflow
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Exercise: Upscaling Workflow
For efficient reservoir simulation, the high-resolution gridblocks in the geological model must be consolidated into coarser gridblocks while maintaining the fluid-flow characteristics of the geologic model. This process is called upscaling. The Upscaler analyzes each fault in the model and, when necessary, uses a clever coarsening technique to create refinements around faults to ensure that fault locations are not changed by the upscaling process.
The Upscaler Workflow lets you upscale 3D grid models containing SGrids, VIP® grids in VDB format, or Rescue models. Once upscaled, the files are saved in VDB format for use in simulation. In addition to outputting standard permeabilities, permeabilities calculated from well-based information, and other properties mapped in the Property mapping panel, the Upscaler also calculates and outputs half-transmissibility multipliers, which can be used in the Nexus software to calculate transmissibilities.
1. In the Nexus View window, click to launch the Upscaler Workflow window.
The first step is to select the fine grid that you want to upscale.
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2. Make sure wfarm.vdb is the 3D grid model.
3. Click Next to go to Property Mapping.
The next step is to map the source properties (that is, the properties on the input grid) to simulator properties and specify the upscaling method to be used.
4. Click the cell under the Target Property column for KX.
5. Double-click KX.
The upscale method is updated automatically.
6. Follow the same steps to map KY, KZ and POR.
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Use the default upscale methods.
7. Click Next to go to Coarsening.
The next step is to define the coarsening parameters.
8. Select the coarsening method to be used for the Columns (I), Rows (J), and Layers (K) from the drop-down list for each, and enter the desired value(s) in the text fields to the right of each direction (refer to the descriptions below).
Different methods can be used in each direction. The available coarsening methods are:
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• Constant Coarsening Factor lets you specify the number of refined cells you want in each coarsened cell. In the example shown below, a factor of three is specified. The software adjusts the odd-numbered cells as necessary to best fit the constant value.
Note
If you have layers with zero pore volumes, select Automatic Layer Lumping (see below) for K to combine the layers instead of using Constant Coarsening. This will ensure that the zero pore volume layers are not combined with adjacent layers during upscaling.
• Number of Coarse Cells lets you specify the total number of coarsened cells you want in the upscaled grid. In the example shown below, five coarsened cells are specified. The software merges the odd-numbered cells as necessary to ensure a total of five.
• User Defined Grouping lets you specify the grouping for each coarse cell. The format for this entry is a list of cell indices separated by commas. In the example below, the values 1, 4, 10 were given. Thus, the first coarse cell includes blocks 1 through 3, the second coarse cell includes blocks 4 through 9, and the last coarse cells include all the remaining cells from 10.
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• Automated Lumping (this option is available only for Layers) allows you to quickly and accurately upscale the refined grid into a simulation grid using a residual optimization technique. If selected, the Layer Lumping step in the workflow is activated. See Automatic Layer Lumping for additional information.
When this option is selected, the value turns red to indicate that it is not being used. When you click Next, the automatic layer lumping is performed. If you then click Previous on the Layer Lumping panel or click Coarsening Parameters in the workflow tree, the first layer in each lumped group is shown in the Values field.
Note
This option is not available if no target properties are mapped to the source properties since the application then uses the input names.
9. Accept the default settings and click Next.
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The next step is used to define and output the upscaled grid. The number of coarsened cells that will be created using the current parameters is shown at the top of the panel. Note that all upscaled grids are saved in VDB format.
You can define a new study and case name. In this exercise, you will accept the default names.
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10. Click . The result is displayed as below.
11. Click to exit Upscaler Workflow window.
12. From the Nexus View window, select File > Load 3D Gird. Navigate to the WS11 directory, if necessary.
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13. From the Select a grid file or directory window, open the newly created file wfarm_upscaled.vdb.
14. The upscaled grid should now be shown. If it isn’t, use the Data Selector window, click the drop-down arrow in the Project field and click wfarm_upscaled.vdb.
15. Click Apply.
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The new view appears as shown below in 3D Viewer.
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Exercise: Creating a Local Grid Refinement
LGRs are useful in areas where a higher density of gridblocks is warranted. Often, gridblock spacing is finer in the vicinity of wells, as needed to model significant variations in pressure or flow near the wellbore.
Define a Region
Using the Region Manager, you can delete, clone, or modify an existing region on a model. You can also create and define a new region. A region can be used to concentrate on areas near wells, faults, or with favorable property characteristics that should retain a finer scale in the simulation scale grid.
1. In the Data Selector window, make sure wfarm.vdb is the working project and CALC is selected for the data class.
2. Set the calculated POR as the viewing property.
3. Click Apply.
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4. In the Nexus View window, click to open the Inventory Manager window.
5. Make sure only to display wfarm:CALC:ROOT.
6. Click Close to exit Inventory Manager.
7. Click from the tool bar in the Nexus View window to launch Region Manager.
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8. Click in the Region Manager window to add a new region.
9. Select Empty region.
10. Click OK to create an empty dynamic region.
A new region called “user_region_0” is displayed.
11. Highlight the user_region_0 region by clicking it.
12. Rename “user_region_0” to “voi”.
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The Add/Remove cells to voi area is activated now.
• From Property lets you define a region using a property range.
• Around Wells lets you select wells around which you want the region defined.
• Around Faults lets you select internal faults of the 3D grid around which you want the region defined.
• In Window lets you enter an extraction window (location of a region) in a text field or using range sliders.
• In Polygon lets you select or create a 2D polygon to add/remove cells in a region.
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• From Dynamic Region lets you select an existing dynamic region in the 3D grid model to initialize a new region.
• From Script lets you define a region using a script.
Next, you will learn how to define a region around wells, around faults and in polygon.
First, you will add a region around wells.
13. Click the Around Wells tab.
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14. Click on icon to select all wells.
15. Specify using a distance of 700 meters to define the region and click Apply.
Now, region voi is defined.
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16. Click on "Display Selected Region(s)" box on Region Manager window, and change the transparency to 60 in the 3D Viewer window:
Next, you will add a region around faults.
17. Add a new empty region.
18. The default new region name is “user_region_0”. Double-click the name to make it editable.
19. Change the name to voi_fault.
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20. Click the Around Faults tab, select the first three faults by pressing Ctrl and clicking, and set the “number of cells” as 3. Check the “Display Selected Region(s)” box.
21. Click Apply.
The information of the voi_fault region is updated.
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The view in 3D Viewer is displayed as below.
Lastly, you will add a region in polygon.
22. Add a new empty region.
23. The default new region name is “user_region_0”. Double-click the name to make it editable.
24. Change the name to voi_polygon.
25. Change the color to yellow.
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26. Click the In Polygon tab, then click to digitize and polygon. Then, go to the Nexus View software to click a few points to draw a polygon. When you finish, click the middle mouse button to complete it.
You have created a polygon.
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27. In the Region Manager window, click Apply to create the new region. Note that the cell count and volume for your polygon may be different from what is shown in the image below.
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Define a Local Grid Refinement
The Refinement Manager can be used to add or remove a local grid refinement (LGR) on a 3D grid. LGRs are useful in areas where a higher density of gridblocks is warranted. Often, gridblock spacing is finer in the vicinity of wells, as needed to model significant variations in pressure or flow near the wellbore. In this exercise, you will create an LGR around wells.
1. Click from the toolbar in the Nexus View window to launch Refinement Manager.
2. Select voi as Region.
3. Check Preview the LGR location.
4. Set Cell Dividers as 2 for I, J and K.
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.
5. Click . 99 LGRs are created.
The view in the Nexus View software is similar to that shown below.
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To view the LGR with wells, highlight the voi region in Region Manager.
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Discussion Points
You should now be able to answer the following questions:
• What does the PowerGrid software do?
• What are the different ways to define a region?
• How do you refine the grids?
• How do you upscale the grids?
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